Tire Tread Rubber Composition

ABSTRACT

Disclosed herein are tire tread rubber compositions comprising a specified elastomer component, reinforcing silica filler, a specified hydrocarbon resin, a cure package, and optionally oil. The elastomer component includes at least one styrene-butadiene rubber having a silica-reactive functional group; and guayule natural rubber.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/052,714, filed Nov. 3, 2020 which is a U.S. national stage ofInternational Application Number PCT/US2019/030094 filed on May 1, 2019,which claims priority to U.S. provisional application Ser. No.62/667,039, filed May 4, 2018, all of which are hereby incorporated byreference in their entirety.

FIELD

The present application is directed to a rubber composition for use intire treads.

BACKGROUND

Tires comprise many components including a road-contacting tread. Theparticular ingredients used in the rubber composition which comprisesthe tire tread may vary. Formulation of tire tread rubber compositionsis a complex science since changes to the formulation which result in animprovement in one property (e.g., rolling resistance) may result indeterioration of another property (e.g., dry traction).

SUMMARY

Disclosed herein are rubber compositions for use in tire treads.

In a first embodiment, a tire tread rubber composition is disclosed. Thecomposition comprises (a) 100 parts of an elastomer componentcomprising: (i) at least 45 parts of one or more styrene-butadienerubbers having a silica-reactive functional group, and (ii) 10-55 partsof natural rubber, polyisoprene, or a combination thereof; (b) at leastone reinforcing silica filler in an amount of 50-150 phr; (c) 11-40 phrof at least one hydrocarbon resin having a Tg of about 35 to about 60°C.; (d) less than 10 phr of oil; and (e) a cure package. According tothe first embodiment, (c) and (d) are present in a total amount of lessthan 50 phr.

In a second embodiment, a tire tread rubber composition is disclosed.The composition comprises: (a) 100 parts of an elastomer componentcomprising: (i) at least 50 parts of one or more styrene-butadienerubbers having a silica-reactive functional group and a Tg of about −65to about −40° C., and (ii) 10-50 parts of natural rubber, polyisoprene,or a combination thereof; (b) at least one reinforcing silica filler inan amount of 50-89 phr; (c) 11-40 phr of at least one hydrocarbon resinhaving a Tg of about 35 to about 60° C.; (d) less than 10 phr of oil;and (e) a cure package. According to the second embodiment, (c) and (d)are present in a total amount of no more than 40 phr and the tire treadrubber composition contains no more than 20 phr of carbon black filler.

In a third embodiment, a tire tread rubber composition is disclosed. Thecomposition comprises: (a) 100 parts of an elastomer componentcomprising: (i) at least 50 parts of two styrene-butadiene rubbershaving a silica-reactive functional group, each having a Tg of about −65to about −40° C. and a Mw of 250,000 to 600,000 grams/mole, (ii) 10-50parts of natural rubber, polyisoprene, or a combination thereof, and(iii) 0-5 phr of polybutadiene rubber; (b) at least one reinforcingsilica filler in an amount of 50-89 phr; (c) 11-40 phr of at least onehydrocarbon resin having a Tg of about 35 to about 60° C.; (d) less than10 phr of oil; and (e) a cure package. According to the thirdembodiment, (c) and (d) are present in a total amount of no more than 40phr and the tire tread rubber composition contains no more than 20 phrof carbon black filler.

In a fourth embodiment, a tire including a tread comprising the tiretread rubber composition according to the first embodiment, the secondembodiment, or the third embodiment is disclosed.

In a fifth embodiment, a process is provided for preparing a tire treadrubber composition according to any one of the first, second, or thirdembodiments, wherein the process comprises utilizing ingredients asdescribed herein for the first, second, or third embodiment,respectively. In other words, according to the fifth embodiment, thetire tread rubber composition is made from ingredients as describedherein for the first, second, or third embodiments.

DETAILED DESCRIPTION

Disclosed herein are rubber compositions for use in tire treads.

In a first embodiment, a tire tread rubber composition is disclosed. Thecomposition comprises (a) 100 parts of an elastomer componentcomprising: (i) at least 45 parts of one or more styrene-butadienerubbers having a silica-reactive functional group, and (ii) 10-55 partsof natural rubber, polyisoprene, or a combination thereof; (b) at leastone reinforcing silica filler in an amount of 50-150 phr; (c) 11-40 phrof at least one hydrocarbon resin having a Tg of about 35 to about 60°C.; (d) less than 10 phr of oil; and (e) a cure package. According tothe first embodiment, (c) and (d) are present in a total amount of lessthan 50 phr.

In a second embodiment, a tire tread rubber composition is disclosed.The composition comprises: (a) 100 parts of an elastomer componentcomprising: (i) at least 50 parts of one or more styrene-butadienerubbers having a silica-reactive functional group and a Tg of about −65to about −40° C., and (ii) 10-50 parts of natural rubber, polyisoprene,or a combination thereof; (b) at least one reinforcing silica filler inan amount of 50-89 ph;, (c) 11-40 phr of at least one hydrocarbon resinhaving a Tg of about 35 to about 60° C.; (d) less than 10 phr of oil;and (e) a cure package. According to the second embodiment, (c) and (d)are present in a total amount of no more than 40 phr and the tire treadrubber composition contains no more than 20 phr of carbon black filler.

In a third embodiment, a tire tread rubber composition is disclosed. Thecomposition comprises: (a) 100 parts of an elastomer componentcomprising: (i) at least 50 parts of two styrene-butadiene rubbershaving a silica-reactive functional group, each having a Tg of about −65to about −40° C. and a Mw of 250,000 to 600,000 grams/mole, (ii) 10-50parts of natural rubber, polyisoprene, or a combination thereof, and(iii) 0-5 phr of polybutadiene rubber; (b) at least one reinforcingsilica filler in an amount of 50-89 phr; (c) 11-40 phr of at least onehydrocarbon resin having a Tg of about 35 to about 60° C.; (d) less than10 phr of oil; and (e) a cure package. According to the thirdembodiment, (c) and (d) are present in a total amount of no more than 40phr and the tire tread rubber composition contains no more than 20 phrof carbon black filler.

In a fourth embodiment, a tire including a tread comprising the tiretread rubber composition according to the first embodiment, the secondembodiment, or the third embodiment is disclosed.

In a fifth embodiment, a process is provided for preparing a tire treadrubber composition according to any one of the first, second, or thirdembodiments, wherein the process comprises utilizing ingredients asdescribed herein for the first, second, or third embodiment,respectively. In other words, according to the fifth embodiment, thetire tread rubber composition is made from ingredients as describedherein for the first, second, or third embodiments.

Definitions

The terminology as set forth herein is for description of theembodiments only and should not be construed as limiting the inventionas a whole.

As used herein, the term “majority” refers to more than 50%.

As used herein, the abbreviation Mn is used for number average molecularweight.

As used herein, the abbreviation Mp is used for peak molecular weight.

As used herein, the abbreviation Mw is used for weight average molecularweight.

Unless otherwise indicated herein, the term “Mooney viscosity” refers tothe Mooney viscosity, ML₁₊₄. As those of skill in the art willunderstand, a rubber composition's Mooney viscosity is measured prior tovulcanization or curing.

As used herein, the term “natural rubber” means naturally occurringrubber such as can be harvested from sources such as Hevea rubber treesand non-Hevea sources (e.g., guayule shrubs and dandelions such as TKS).In other words, the term “natural rubber” should be construed so as toexclude synthetic polyisoprene.

As used herein, the term “phr” means parts per one hundred parts rubber.The one hundred parts rubber is also referred to herein as 100 parts ofan elastomer component.

As used herein the term “polyisoprene” means synthetic polyisoprene. Inother words, the term is used to indicate a polymer that is manufacturedfrom isoprene monomers, and should not be construed as includingnaturally occurring rubber (e.g., Hevea natural rubber, guayule-sourcednatural rubber, or dandelion-sourced natural rubber). However, the termpolyisoprene should be construed as including polyisoprenes manufacturedfrom natural sources of isoprene monomer.

As used herein, the term “tread,” refers to both the portion of a tirethat comes into contact with the road under normal inflation and load aswell as any subtread.

Tire Tread Rubber Composition

As mentioned above, the first-third embodiments are directed to a tiretread rubber composition. The subject rubber compositions are used inpreparing treads for tires, generally by a process which includesforming of a tread pattern by molding and curing one of the subjectrubber compositions. Thus, the tire treads will contain a cured form ofone of the tire tread rubber compositions. The tire tread rubbercompositions may be present in the form of a tread which has been formedbut not yet incorporated into a tire and/or they may be present in atread which forms part of a tire.

According to the first-fourth embodiments disclosed herein, the Tg ofthe overall rubber composition may vary. In certain embodiments of thefirst-fourth embodiments, the rubber composition has a Tg of about −40°C. to less than 0° C. In certain embodiments of the first-fourthembodiments, the rubber composition has a Tg of −40° C. to less than 0°C. (e.g., −40, −35, −30, −25, −20, −15, −10, −5, −4, −3, −2, or ° C.),about −40° C. to about −20° C., −40° C. to −20° C. (e.g. −40, −38, −36,−34, −32, −30, −28, −26, −24, −22, or −20° C). , about −35° C. to about−25° C., −35° C. to −25° C. (e.g., −35, −34 −33, −32, −31, −30, −29,−28, −27, −26, or −25° C.), about −20° C. to less than 0° C., or −20° C.to less than 0° C. (e.g., −20, −19, −18, −17, −16, −15, −14, −13, −12,−11, −10, −9, −8, −7, −6, −5, −4, −3, −2, or −1° C.). In certainembodiments of the first-fourth embodiments wherein the rubbercomposition has a Tg within the range of −40 to −20° C., the totalamount of styrene-butadiene rubber(s) having a silica-reactivefunctional group and a Tg of about −65 to about −40 C is 60 phr or more(e.g., 60 phr, 65 phr, 70 phr, 75 phr, 80 phr, or more) or 60-80 phr.

Elastomer Component

As mentioned above, according to the first-fourth embodiments, the tiretread rubber composition comprises (includes) 100 parts of an elastomercomponent. The ingredients of the elastomer component include one ormore styrene-butadiene rubbers having a silica-reactive functionalgroup; and natural rubber, polyisoprene, or a combination thereof. Thetotal amount of 100 parts of elastomer or rubber is used so that theamount of other ingredients may be listed in amounts of phr or thenumber of parts per hundred parts rubber (or 100 parts of the elastomercomponent). As a non-limiting example, for a rubber compositioncontaining 75 parts of styrene-butadiene rubber having a silica-reactivefunctional group, 25 parts of natural rubber and 75 parts of reinforcingsilica filler, the amount of silica filler can also be described as 75phr.

As mentioned above, according to the first embodiment, the 100 parts ofelastomer component comprises (includes) (i) at least 45 parts (e.g.,45, 50, 55, 60, 65, 70, 75, 80, 85, or 90 parts) of one or morestyrene-butadiene rubbers having a silica-reactive functional group, and(ii) 10-55 (e.g., 10, 15, 20, 25, 30, 35, 40, 45, 50 or 55 parts) partsof natural rubber, polyisoprene, or a combination thereof. In certainembodiments of the first embodiment, only one styrene-butadiene rubberhaving a silica-reactive functional group is used for (i). In otherembodiments of the first embodiment, two styrene-butadiene rubbers eachhaving a silica-reactive functional group are used for (i). In yet otherembodiments of the first embodiment, three (or more) styrene-butadienerubbers each having a silica-reactive functional group are used for (i).According to the first embodiment, when more than one styrene-butadienerubber having a silica-reactive functional group is used for (i), thetotal amount of all such rubbers is at least 45 parts, at least 50parts, at least 60 parts, etc. In certain embodiments of the firstembodiment, the elastomer component comprises (includes) at least 50parts (e.g., 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 65, 70, 75, 80,85, or 90 parts) or at least 60 parts (e.g., 60, 61, 62, 63, 64, 65, 66,67, 68, 69, 70, 75, 80, 85, or 90 parts) of one or morestyrene-butadiene rubbers having a silica-reactive functional group. Incertain embodiments of the first embodiment, the elastomer componentcomprises (includes) 10-49 parts (e.g., 10, 11, 12, 13, 14, 15, 16, 17,18, 19, 20, 25, 30, 35, 40, 45, 46, 47, 48, or 49 parts), 20-49 parts(e.g., 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 46, 47,48, or 49 parts), 20-50 (e.g., 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,30, 35, 40, 45, 46, 47, 48, 49, or 50 parts), or 10-40 parts (e.g., 10,11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, or 40 parts) ofnatural rubber, polyisoprene, or a combination thereof. According to thefirst embodiment, (ii) may consist of natural rubber, polyisoprene, or acombination thereof. In certain embodiments of the first embodiment,(ii) consists (only) of natural rubber. In other embodiments of thefirst embodiment, (ii) consists (only) of polyisoprene. In certainembodiments of the first embodiment, the only rubbers present in theelastomer component are those according to (i) and (ii). In otherembodiments of the first embodiment, the 100 parts of elastomercomponent includes in addition to (i) and (ii), one or more additionalrubbers (iii). According to the first embodiment, when one or moreadditional rubbers (iii) is present, the amount will generally belimited, preferably to no more than 20 parts, no more than 15 parts, nomore than 10 parts, or no more than 5 parts. In certain embodiments ofthe first embodiment, the elastomer component includes no more than 5phr (e.g., 5, 4, 3, 2, 1 or 0 phr) of polybutadiene rubber. In certainembodiments of the first embodiment, one or more additional rubbers(iii) are selected from diene monomer-containing rubbers; in certainsuch embodiments, the one or more additional rubbers (iii) are selectedfrom the group consisting of polybutadiene rubber, non-functionalizedstyrene-butadiene rubbers, styrene-butadiene rubbers functionalized withnon-silica-reactive groups (e.g., a carbon black-reactive functionalgroup), styrene-isoprene rubber, butadiene-isoprene-rubber,styrene-isoprene-butadiene rubber, butyl rubber (both halogenated andnon-halogenated), ethylene-propylene rubber (EPR), ethylene-butylenerubber (EBR), ethylene-propylene-diene rubber (EPDM), and combinationsthereof. In yet other embodiments of the first embodiment, the one ormore additional rubbers are selected from one or more styrene-butadienerubbers other than the styrene-butadiene rubber (i), e.g., a SBR that isnot functionalized with a silica-reactive functional group and/or has aTg of greater than −40° C. or less than −65° C.; or from a diene-monomercontaining rubber other than the natural rubber or polyisoprene (ii); ora combination thereof.

As mentioned above, according to the second embodiment, the 100 parts ofelastomer component comprises (includes) (i) at least 50 parts (e.g.,50, 55, 60, 65, 70, 75, 80, 85, or 90 parts) of one or morestyrene-butadiene rubbers having a silica-reactive functional group, and(ii) 10-50 parts of natural rubber, polyisoprene, or a combinationthereof. In certain embodiments of the second embodiment, only onestyrene-butadiene rubber having a silica-reactive functional group isused for (i). In other embodiments of the second embodiment, twostyrene-butadiene rubbers each having a silica-reactive functional groupare used for (i). In yet other embodiments of the second embodiment,three (or more) styrene-butadiene rubbers each having a silica-reactivefunctional group are used for (i). According to the second embodiment,when more than one styrene-butadiene rubber having a silica-reactivefunctional group is used for (i), the total amount is all such rubbersis at least 50 parts, at least 60 parts, etc. In certain embodiments ofthe second embodiment, the elastomer component comprises (includes) atleast 60 parts (e.g., 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 75,80, 85, or 90 parts) or at least 70 parts (e.g., 70, 71, 72, 73, 74, 75,76, 77, 78, 79, 80, 85, or 90 parts) of one or more styrene-butadienerubbers having a silica-reactive functional group. In certainembodiments of the second embodiment, the elastomer component comprises(includes) 10-49 parts (e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,20, 25, 30, 35, 40, 45, 46, 47, 48, or 49 parts), 20-49 parts (e.g., 20,21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 46, 47, 48, or 49parts), 20-50 (e.g., 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40,45, 46, 47, 48, 49, or 50 parts), or 10-40 parts (e.g., 10, 11, 12, 13,14, 15, 16, 17, 18, 19, 20, 25, 30, 35, or 40 parts) of natural rubber,polyisoprene, or a combination thereof. According to the secondembodiment, (ii) may consist of natural rubber, polyisoprene, or acombination thereof. In certain embodiments of the second embodiment,(ii) consists (only) of natural rubber. In other embodiments of thesecond embodiment, (ii) consists (only) of polyisoprene. In certainembodiments of the second embodiment, the only rubbers present in theelastomer component are those according to (i) and (ii), i.e., the 100parts of elastomer component consists of (only) (i) and (ii), in theamounts discussed above. In other embodiments of the second embodiment,the 100 parts of elastomer component includes in addition to (i) and(ii), one or more additional rubbers (iii). According to the secondembodiment, when one or more additional rubbers (iii) is present, theamount will generally be limited preferably to no more than 20 parts, nomore than 15 parts, no more than 10 parts, or no more than 5 parts. Incertain embodiments of the second embodiment, the elastomer componentincludes no more than 5 phr (e.g., 5, 4, 3, 2, 1 or 0 phr) ofpolybutadiene rubber. In certain embodiments of the second embodiment,one or more additional rubbers (iii) are selected from dienemonomer-containing rubbers; in certain such embodiments, the one or moreadditional rubbers (iii) are selected from the group consisting ofpolybutadiene rubber, non-functionalized styrene-butadiene rubber,styrene-butadiene rubber functionalized with a non-silica-reactivefunctional group (e.g., a carbon-black reactive functional group),styrene-isoprene rubber, butadiene-isoprene-rubber,styrene-isoprene-butadiene rubber, butyl rubber (both halogenated andnon-halogenated), neoprene (polychloroprene), ethylene-propylene rubber,ethylene-propylene-diene rubber (EPDM), and combinations thereof. In yetother embodiments of the second embodiment, the one or more additionalrubbers are selected from one or more styrene-butadiene rubbers otherthan the styrene-butadiene rubber (i), e.g., a SBR that is notfunctionalized with a silica-reactive functional group or a SBR that hasa Tg of greater than −40° C. or less than −65° C.; or from adiene-monomer containing rubber other than the natural rubber orpolyisoprene (ii); or a combination thereof.

According to the third embodiment, the 100 parts of elastomer componentcomprises (includes) (i) at least 50 parts of two styrene-butadienerubbers each having a silica-reactive functional group, each having a Tgof about −65 to about −40° C. and a Mw of 250,000 to 600,000 grams/mole,(ii) 10-50 parts of natural rubber, polyisoprene, or a combinationthereof, and (iii) 0-5 phr of polybutadiene rubber. In certainembodiments of the third embodiment, the 100 parts of elastomercomponent consists of (i) at least 50 parts of two styrene-butadienerubbers each having a silica-reactive functional group, each having a Tgof about −65 to about −40° C. and a Mw of no more than 600,000grams/mole, (ii) 10-50 parts of natural rubber, polyisoprene, or acombination thereof, and (iii) 0-5 phr of polybutadiene rubber. Incertain embodiments of the third embodiment, the elastomer componentcomprises (includes) at least 55 parts (e.g., 55, 56, 57, 58, 59, 60,65, 70, 75, 80, 85, or 90 parts), at least 60 parts (e.g., 60, 61, 62,63, 64, 65, 66, 67, 68, 69, 70, 75, 80, 85, or 90 parts) or at least 70parts (e.g., 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 85, or 90parts) in total of the two styrene-butadiene rubbers having asilica-reactive functional group of (i). In certain embodiments of thethird embodiment, the elastomer component comprises (includes) 10-49parts (e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40,45, 46, 47, 48, or 49 parts), 20-49 parts (e.g., 20, 21, 22, 23, 24, 25,26, 27, 28, 29, 30, 35, 40, 45, 46, 47, 48, or 49 parts), 20-50 (e.g.,20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 46, 47, 48, 49,or 50 parts), or 10-40 parts (e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18,19, 20, 25, 30, 35, or 40 parts) of natural rubber, polyisoprene, or acombination thereof. According to the third embodiment, (ii) may consistof natural rubber, polyisoprene, or a combination thereof. In certainembodiments of the third embodiment, (ii) consists (only) of naturalrubber. In other embodiments of the third embodiment, (ii) consists(only) of polyisoprene. In certain embodiments of the third embodiment,the only rubbers present in the elastomer component are those accordingto (i), (ii) and (iii), i.e., the 100 parts of elastomer componentconsists (only) of (i), (ii) and (iii), in the amounts discussed above.In other embodiments of the third embodiment, the 100 parts of elastomercomponent includes in addition to (i), (ii) and (iii), one or moreadditional rubbers (iv). According to the third embodiment, when one ormore additional rubbers (iv) is present, the amount will generally belimited preferably to no more than 20 parts, no more than 15 parts, nomore than 10 parts, or no more than 5 parts. In certain embodiments ofthe third embodiment, one or more additional rubbers (iv) are selectedfrom diene monomer-containing rubbers; in certain such embodiments, theone or more additional rubbers (iii) are selected from the groupconsisting of non-functionalized styrene-butadiene rubber,styrene-butadiene functionalized with a non-silica-reactive functionalgroup (e.g., a carbon-black reactive functional group), styrene-isoprenerubber, butadiene-isoprene-rubber, styrene-isoprene-butadiene rubber,butyl rubber (both halogenated and non-halogenated), neoprene(polychloroprene), ethylene-propylene rubber, ethylene-propylene-dienerubber (EPDM), and combinations thereof. In yet other embodiments of thethird embodiment, the one or more additional rubbers are selected fromone or more styrene-butadiene rubbers other than the styrene-butadienerubber (i), e.g., a SBR that is not functionalized with asilica-reactive functional group, has a Tg of greater than −40° C. orless than −65° C. and/or has a Mw of greater than 600,000 grams/mole;from a diene-monomer containing rubber other than the natural rubber orpolyisoprene (ii); from one or more polybutadiene rubbers other than thepolybutadiene rubber (iii), e.g., a BR having a cis bond content of lessthan 95% e.g., a polybutadiene having a low cis 1, 4 bond content (e.g.,a polybutadiene having a cis 1,4 bond content of less than 50%, lessthan 45%, less than 40%, etc.) and/or a Tg of less than −101° C.; or acombination thereof.

As mentioned above, according to the second and third embodimentsdisclosed herein, the elastomer component comprises (includes) at least50 parts of at least one (second embodiment) or at least two (thirdembodiment) styrene-butadiene rubber(s) having a silica-reactivefunctional group, each having a Tg of about −65 to about −40° C. (e.g.,−65, −63, −61, −60, −58, −56, −55, −54, −52, −50, −48, −46, −45, −44,−42, or −40° C.). According to the third embodiment, the Tg of the atleast one styrene-butadiene rubber having a silica-reactive functionalgroup may vary. In certain embodiments of the first embodiment, the atleast one styrene-butadiene rubber having a silica reactive group has aTg of about −75 to about −30° C., −75 to −30° C. (e.g., −75, −73, −71,−70, −68, −66, −65, −63, −61, −60, −58, −56, −55, −54, −52, −50, −48,−46, −45, −44, −42, −40, −38, −36, −34, −32, or −30° C.), about −65 toabout −40° C., or −65 to −40° C. (e.g., −65, −63, −61, −60, −58, −56,−55, −54, −52, −50, −48, −46, −45, −44, −42, or −40° C.). The Tg valuesreferred to herein for elastomers represent a Tg measurement made uponthe elastomer without any oil-extension. In other words, for anoil-extended elastomer, the Tg values above refer to the Tg prior to oilextension or to a non-oil-extended version of the same elastomer.Elastomer or polymer Tg values may be measured using a differentialscanning calorimeter (DSC) instrument, such as manufactured by TAInstruments (New Castle, Delaware), where the measurement is conductedusing a temperature elevation of 10° C./minute after cooling at −120° C.Thereafter, a tangent is drawn to the base lines before and after thejump of the DSC curve. The temperature on the DSC curve (read at thepoint corresponding to the middle of the two contact points) can be usedas Tg. In yet other embodiments of the second and third embodiments, theone or more additional rubbers are selected from one or morestyrene-butadiene rubbers other than the styrene-butadiene rubber (i),e.g., a SBR that is not functionalized with a silica-reactive functionalgroup, has a Tg of greater than −40° C. or less than −65° C. and/or hasa Mw of greater than 600,000 grams/mole; from a diene-monomer containingrubber other than the natural rubber or polyisoprene (ii); from one ormore polybutadiene rubbers other than the polybutadiene rubber (iii),e.g., a BR having a cis bond content of less than 95% e.g., apolybutadiene having a low cis 1, 4 bond content (e.g., a polybutadienehaving a cis 1,4 bond content of less than 50%, less than 45%, less than40%, etc.) and/or a Tg of less than −101° C.; or a combination thereof.

According to the first-fourth embodiments, the styrene monomer content(i.e., weight percent of the polymer chain comprising styrene units asopposed to butadiene units) of the styrene-butadiene rubber(s) having asilica-reactive functional group which are used for (i) may vary. Incertain embodiments of the first-fourth embodiments, the styrene contentof the styrene-butadiene rubber(s) having a silica-reactive functionalgroup which are used for (i) have a styrene monomer content of about 10to about 50% (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%) byweight of the total monomer content (i.e., 1,3-butadiene +styrene),including 10-50% by weight, about 18 to about 40% by weight, 18-40% byweight, about 10 to about 20% by weight, or 10-20% by weight.

According to the first-fourth embodiments, the vinyl bond content (i.e.,1,2-microstructure) of the styrene-butadiene rubber(s) having asilica-reactive functional group which are used for (i) may vary. Incertain embodiments of the first-fourth embodiments, thestyrene-butadiene rubber(s) having a silica-reactive functional groupwhich are used for (i) may have a vinyl bond content of about 10 toabout 60%, 10-60% (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%,55% or 60%), about 10 to about 50%, 10-50% (e.g., 10%, 15%, 20%, 25%,30%, 35%, 40%, 45%, or 50%), about 15 to about 40% or 15-40% (e.g., 15%,20%, 25%, 30%, 35%, or 40%). The styrene-butadiene rubber(s) having asilica-reactive functional group which are used for (i) may have a vinylbond content within one of the foregoing ranges, optionally incombination with one or more of the Mw, Mn, and/or Mw/Mn rangesdiscussed below, and in certain embodiments optionally in combinationwith one of the styrene monomer contents discussed above. The vinyl bondcontents referred to herein should be understood as being for theoverall vinyl bond content in the SBR polymer chain rather than of thevinyl bond content in the butadiene portion of the SBR polymer chain,and can be determined by H¹-NMR and C¹³-NMR (e.g., using a 300 MHzGemini 300 NMR Spectrometer System (Varian)).

According to the first-fourth embodiments, the particularfunctionalizing group used in preparing the one or morestyrene-butadiene rubbers having a silica-reactive functional group mayvary. One or more than one type of silica-reactive functional group maybe utilized for each rubber. The silica-reactive functional group may bepresent at the head of the polymer, at the tail of the polymer, alongthe backbone of the polymer chain, or a combination thereof. Functionalgroups present at one or both terminals of a polymer are generally theresult of the use of a functional initiator, a functional terminator, orboth. Alternatively or additionally, the silica-reactive functionalgroup may be present as a result of coupling of multiple polymer chainsusing a coupling agent (as described below). Non-limiting examples ofsilica-reactive functional groups generally include nitrogen-containingfunctional groups, silicon-containing functional groups, oxygen- orsulfur-containing functional groups, and metal-containing functionalgroups.

Non-limiting examples of nitrogen-containing functional groups that canbe utilized in certain embodiments of the first-fourth embodiments as asilica-reactive functional group in the styrene-butadiene rubber of (i)include, but are not limited to, a substituted or unsubstituted aminogroup, an amide residue, an isocyanate group, an imidazolyl group, anindolyl group, an imino group, a nitrile group, a pyridyl group, and aketimine group. The foregoing substituted or unsubstituted amino groupshould be understood to include a primary alkylamine, a secondaryalkylamine, or a cyclic amine, and an amino group derived from asubstituted or unsubstituted imine. In certain embodiments of thefirst-fourth embodiments, the styrene-butadiene rubber of (i) comprisesat one silica-reactive functional group selected from the foregoing listof nitrogen-containing functional groups.

In certain embodiments of the first-fourth embodiments, thestyrene-butadiene rubber of (i) includes a silica-reactive functionalgroup from a compound which includes nitrogen in the form of an iminogroup. Such an imino-containing functional group may be added byreacting the active terminal of a polymer chain with a compound havingthe following formula

wherein R, R′, R″, and R′″ each independently are selected from a grouphaving 1 to 18 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, or 18 carbon atoms) selected from the groupconsisting of an alkyl group, an allyl group, and an aryl group; m and nare integers of 1 to 20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, 18, 19, or 20) and 1 to 3 (1, 2, or 3),respectively. Each of R, R′, R″, and R′″ are preferably hydrocarbyl andcontain no heteroatoms. In certain embodiments of the first-fourthembodiments, each R and R′ are independently selected from an alkylgroup having 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6 carbonatoms), preferably 1 to 3 carbon atoms (e.g., 1, 2, or 3 carbon atoms).In certain embodiments of the first-fourth embodiments, m is an integerof 2 to 6 (e.g., 2, 3, 4, 5, or 6), preferably 2 to 3. In certainembodiments of the first-fourth embodiments, R′″ is selected from agroup having 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6 carbonatoms), preferably 2 to 4 carbon atoms (e.g., 2, 3, or 4 carbon atoms).In certain embodiments of the first-fourth embodiments, R″ is selectedfrom an alkyl group having 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or6 carbon atoms), preferably 1 to 3 carbon atoms (e.g., 1, 2, or 3 carbonatoms), most preferably 1 carbon atom (e.g., methyl). In certainembodiments of the first-fourth embodiments, n is 3 resulting in acompound with a trihydrocarboxysilane moiety such as a trialkoxysilanemoiety. Non-limiting examples of compounds having an imino group andmeeting formula (I) above, which are suitable for providing thesilica-reactive functional group for the styrene-butadiene rubber of(i), include, but are not limited to,N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propaneamine,N-(1-methylethylidene)-3-(triethoxysilyI)-1-propaneamine,N-ethylidene-3-(triethoxysilyl)-1-propaneamine,N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propaneamine, andN-(4-N,N-dimethylaminobenzylidene)-3-(triethoxysilyl)-1-propaneamine.

Non-limiting examples of silicon-containing functional groups that canbe utilized in certain embodiments of the first-fourth embodiments as asilica-reactive functional group in the styrene-butadiene rubber of (i)include, but are not limited to, an organic silyl or siloxy group, andmore precisely, the such functional group may be selected from analkoxysilyl group, an alkylhalosilyl group, a siloxy group, analkylaminosilyl group, and an alkoxyhalosilyl group. Optionally, theorganic silyl or siloxy group may also contain one or more nitrogens.Suitable silicon-containing functional groups for use in functionalizingdiene-based elastomer also include those disclosed in U.S. Pat. No.6,369,167, the entire disclosure of which is herein incorporated byreference. In certain embodiments of the first-fourth embodiments, thestyrene-butadiene rubber of (i) comprises at least one silica-reactivefunctional group selected from the foregoing list of silicon-containingfunctional groups.

In certain preferred embodiments of the first-fourth embodiments, thestyrene-butadiene rubber of (i) includes a silica-reactive functionalgroup which includes a silicon-containing functional group having asiloxy group (e.g., a hydrocarbyloxysilane-containing compound), whereinthe compound optionally includes a monovalent group having at least onefunctional group. Such a silicon-containing functional group may beadded by reacting the active terminal of a polymer chain with a compoundhaving the following formula (II):

wherein A¹ represents a monovalent group having at least one functionalgroup selected from epoxy, isocyanate, imine, cyano, carboxylic ester,carboxylic anhydride, cyclic tertiary amine, non-cyclic tertiary amine,pyridine, silazane and sulfide; R^(c) represents a single bond or adivalent hydrocarbon group having from 1 to 20 carbon atoms (e.g., 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20carbon atoms); R^(d) represents a monovalent aliphatic hydrocarbon grouphaving 1 to 20 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms), a monovalentaromatic hydrocarbon group having 6 to 18 carbon atoms (e.g., 6, 7, 8,9, 10, 11, 12, 13, 14, 15, 16, 17, or 18 carbon atoms) or a reactivegroup; R^(e) represents a monovalent aliphatic hydrocarbon group having1 to 20 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16, 17, 18, 19, or 20 carbon atoms) or a monovalent aromatichydrocarbon group having 6 to 18 carbon atoms (e.g., 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, or 18 carbon atoms); b is an integer of 0 to 2;when more than one R^(d) or OR^(e) are present, each R^(d) and/or OR^(e)may be the same as or different from each other; and an active proton isnot contained in a molecule) and/or a partial condensation productthereof. As used herein, a partial condensation product refers to aproduct in which a part (not all) of a SiOR group in thehydrocarbyloxysilane compound is turned into a SiOSi bond bycondensation. In certain embodiments of the first-fourth embodiments, atleast one of the following is met: (a) R^(c) represents a divalenthydrocarbon group having 1 to 12 carbon atoms (e.g., 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 11, or 12 carbon atoms), 2 to 6 carbon atoms (e.g., 2, 3,4, 5, or 6 carbon atoms), or 2 to 3 carbon atoms (e.g., 2 or 3 carbonatoms); (b) R^(e) represents a monovalent aliphatic hydrocarbon grouphaving 1 to 12 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or12 carbon atoms), 2 to 6 carbon atoms (e.g., 2, 3, 4, 5, or 6 carbonatoms), or 1 to 2 carbon atoms or a monovalent aromatic hydrocarbongroup having 6 to 8 carbon atoms; (c) R^(d) represents a monovalentaliphatic hydrocarbon group having 1 to 12 carbon atoms(e.g., 1, 2, 3,4, 5, 6, 7, 8, 9, 10, 11, or 12 carbon atoms), 2 to 6 carbon atoms(e.g., 2, 3, 4, 5, or 6 carbon atoms), or 1 to 2 carbon atoms or amonovalent aromatic hydrocarbon group having 6 to 8 carbon atoms; incertain such embodiments, each of (a), (b) and (c) are met and R^(c),R^(e) and R^(d) are selected from one of the foregoing groups.

In certain embodiments of the first-fourth embodiments, the functionalgroup of the styrene butadiene rubber of (i) results from a compoundrepresented by Formula (II) wherein A¹ has at least one epoxy group.Non-limiting specific examples of such compounds include2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane,(2-glycidoxyethyl)methyldimethoxysilane,3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane,(3-glycidoxypropyl)-methyldimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltriethoxysilane,2-(3,4-epoxycyclohexyl)ethyl(methyl)dimethoxysilane and the like. Amongthem, 3-glycidoxypropyltrimethoxysilane and2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane are particularly suited.

In certain embodiments of the first-fourth embodiments, the functionalgroup of the styrene butadiene rubber of (i) results from a compoundrepresented by Formula (II) wherein Al has at least one isocyanategroup. Non-limiting specific examples of such compounds include3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane,3-isocyanatopropylmethyldiethoxysilane,3-isocyanatopropyltriisopropoxysilane and the like, and among them,3-isocyanatopropyltrimethoxysilane is particularly preferred.

In certain embodiments of the first-fourth embodiments, the functionalgroup of the styrene butadiene rubber of (i) results from a compoundrepresented by Formula (II) wherein A¹ has at least one imine group.Non-limiting specific examples of such compounds includeN-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propaneamine,N-(1-methylethylidene)-3-(triethoxysily)-1-propaneamine,N-ethylidene-3-(triethoxysilyl)-1-propaneamine,N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propaneamine,N-(4-N,N-dimethylaminobenzylidene)-3-(triethoxysilyl)-1-propaneamine,N-(cyclohexylidene)-3-(triethoxysilyl)-1-propaneamine andtrimethoxysilyl compounds, methyldiethoxysilyl compounds,ethyldimethoxysilyl compounds and the like each corresponding to theabove triethoxysilyl compounds. Among them,N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propaneamine andN-(1-methylpropylidene)-3-(triethoxysilyl)-1-propaneamine areparticularly suited. Also, the imine(amidine) group-containing compoundsinclude preferably 1-[3-trimethoxysilyl]propyl]-4,5-dihydroimidazole,3-(1-hexamethyleneimino)propyl(triethoxy)silane,(1-hexamethyleneimino)methyl(trimethoxy)silane,N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole,N-(3-isopropoxysilylpropyl)-4,5-dihydroimidazole,N-(3-methyldiethoxysilylpropyl)-4,5-dihydroimidazole and the like, andamong them, N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole andN-(3-isopropoxysilylpropyl)-4,5-dihydroimidazole are preferred.

In certain embodiments of the first-fourth embodiments, the functionalgroup of the styrene butadiene rubber of (i) results from a compoundrepresented by Formula (II) wherein Al has at least one carboxylic estergroup. Non-limiting specific examples of such compounds include3-methacryloyloxypropyltriethoxysilane,3-methacryloyloxypropyltrimethoxysilane,3-methacryloyloxypropylmethyldiethoxysilane,3-methacryloyloxypropyltriisopropoxysilane and the like, and among them,3-methacryloyloxypropyltriethoxysilane is preferred.

In certain embodiments of the first-fourth embodiments, the functionalgroup of the styrene butadiene rubber of (i) results from a compoundrepresented by Formula (II) wherein Al has at least one carboxylicanhydride group. Non-limiting specific examples of such compoundsinclude 3-trimethoxysilylpropylsuccinic anhydride,3-triethoxysilylpropylsuccinic anhydride,3-methyldiethoxysilylpropylsuccinic anhydride and the like, and amongthem, 3-triethoxysilylpropylsuccinic anhydride is preferred.

In certain embodiments of the first-fourth embodiments, the functionalgroup of the styrene butadiene rubber of (i) results from a compoundrepresented by Formula (II) wherein A¹ has at least one cyano group.Non-limiting specific examples of such compounds include2-cyanoethylpropyltriethoxysilane and the like.

In certain embodiments of the first-fourth embodiments, the functionalgroup of the styrene butadiene rubber of (i) results from a compoundrepresented by Formula (II) wherein A¹ has at least one cyclic tertiaryamine group. Non-limiting specific examples of such compounds include3-(1-hexamethyleneimino)propyltriethoxysilane,3-(1-hexamethyleneimino)propyltrimethoxysilane,(1-hexamethyleneimino)methyltriethoxysilane,(1-hexamethyleneimino)methyltrimethoxysilane,2-(1-hexamethyleneimino)ethyltriethoxysilane,3-(1-hexamethyleneimino)ethyltrimethoxysilane,3-(1-pyrrolidinyl)propyltrimethoxysilane,3-(1-pyrrolidinyl)propyltriethoxysilane,3-(1-heptamethyleneimino)propyltriethoxysilane,3-(1-dodecamethyleneimino)propyltriethoxysilane,3-(1-hexamethyleneimino)propyldiethoxymethylsilane,3-(1-hexamethyleneimino)propyldiethoxyethylsilane,3-[10-(triethoxysilyl)decyl]-4-oxazoline and the like. Among them,3-(1-hexamethyleneimino)propyltriethoxysilane and(1-hexamethyleneimino)methyltriethoxysilane can preferably be listed.

In certain embodiments of the first-fourth embodiments, the functionalgroup of the styrene butadiene rubber of (i) results from a compoundrepresented by Formula (II) wherein A¹ has at least one non-cyclictertiary amine group. Non-limiting specific examples of such compoundsinclude 3-dimethylaminopropyltriethoxysilane,3-dimethylaminopropyltrimethoxysilane,3-diethylaminopropyltriethoxysilane,3-dimethylaminopropyltrimethoxysilane,2-dimethylaminoethyltriethoxysilane,2-dimethylaminoethyltrimethoxysilane,3-dimethylaminopropyldiethoxymethylsilane,3-dibutylaminopropyltriethoxysilane and the like, and among them,3-dimethylaminopropyltriethoxysilane and3-diethylaminopropyltriethoxysilane are suited.

In certain embodiments of the first-fourth embodiments, the functionalgroup of the styrene butadiene rubber of (i) results from a compoundrepresented by Formula (II) wherein A¹ has at least one pyridine group.Non-limiting specific examples of such compounds include2-trimethoxysilylethylpyridine and the like.

In certain preferred embodiments of the first-fourth embodiments, thefunctional group of the styrene butadiene rubber of (i) results from acompound represented by Formula (II) wherein A¹ has at least onesilazane group. Non-limiting specific examples of such compounds includeN,N-bis(trimethylsilyl)-aminopropylmethyldimethoxysilane,1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane,N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane,N,N-bis(trimethylsilyl)aminopropyltriethoxysilane,N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane,N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane,N,N-bis(trimethylsilyl)aminoethyltriethoxysilane,N,N-bis(trimethylsilyl)aminoethylmethyldimethoxysilane,N,N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane and the like.N,N-bis(trimethylsilyl)aminopropyltriethoxysilane,N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane or1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane are particularlypreferred.

In those embodiments of the first-fourth embodiments wherein asilica-reactive functional group according to formula (II) is usedwherein A¹ contains one or more protected nitrogens (as discussed indetail above), the nitrogen may be deprotected or deblocked byhydrolysis or other procedures to convert the protected nitrogen(s) intoa primary nitrogen. As a non-limiting example, a nitrogen bonded to twotrimethylsilyl groups could be deprotected and converted to a primaryamine nitrogen (such a nitrogen would still be bonded to the remainderof the formula (II) compound). Accordingly, in certain embodiments ofthe first-fourth embodiments wherein a silica-reactive functional groupof the styrene-butadiene rubber results from use of a compound accordingto formula (II) wherein A¹ contains one or more protected nitrogens, thefunctionalized polymer can be understood as containing a functionalgroup resulting from a deprotected (or hydrolyzed) version of thecompound.

Non-limiting examples of oxygen- or sulfur-containing functional groupsthat can be utilized in certain embodiments of the first-fourthembodiments as a silica-reactive functional group in thestyrene-butadiene rubber of (i) include, but are not limited to, ahydroxyl group, a carboxyl group, an epoxy group, a glycidoxy group, adiglycidylamino group, a cyclic dithiane-derived functional group, anester group, an aldehyde group, an alkoxy group, a ketone group, athiocarboxyl group, a thioepoxy group, a thioglycidoxy group, athiodiglycidylamino group, a thioester group, a thioaldehyde group, athioalkoxy group, and a thioketone group. In certain embodiments of thefirst-fourth embodiments, the foregoing alkoxy group may be analcohol-derived alkoxy group derived from a benzophenone. In certainembodiments of the first-fourth embodiments, the styrene-butadienerubber of (i) comprises at least silica-reactive functional groupselected from the foregoing list of oxygen- or sulfur-containingfunctional groups.

According to the first-fourth embodiments, the one or morestyrene-butadiene rubbers having a silica-reactive functional group of(i) may be prepared by either solution polymerization or by emulsionpolymerization. In certain preferred embodiments of the first-fourthembodiments, the only styrene-butadiene rubbers having a silica-reactivefunctional group used in (i) are prepared by solution polymerization. Inother embodiments of the first-fourth embodiments, the onlystyrene-butadiene rubbers having a silica-reactive functional group usedin (i) are prepared by emulsion polymerization. In certain embodimentsof the first-fourth embodiments, when more than one styrene-butadienerubber having a silica-reactive functional group is used for (i) therubbers are a combination of solution polymerized SBR and emulsionpolymerized SBR (e.g., one solution SBR and one emulsion SBR).

In certain embodiments of the first-fourth embodiments, a functionalizedand coupled form of the styrene-butadiene rubber of (i) can be utilized.Such an effect can be achieved by treating the living polymer with bothcoupling and functionalizing agents, which serve to couple some chainsand functionalize other chains. The combination of coupling agent andfunctionalizing agent can be used at various molar ratios.Alternatively, in certain embodiments of the first-fourth embodiments,the styrene-butadiene rubber of (i) may be silica-reactive merely fromthe result of coupling. Although the terms coupling and functionalizingagents have been employed in this specification, those skilled in theart appreciate that certain compounds may serve both functions. That is,certain compounds may both couple and provide the polymer chains with afunctional group. Those skilled in the art also appreciate that theability to couple polymer chains may depend upon the amount of couplingagent reacted with the polymer chains. For example, advantageouscoupling may be achieved where the coupling agent is added in a one toone ratio between the equivalents of lithium on the initiator andequivalents of leaving groups (e.g., halogen atoms) on the couplingagent. Non-limiting examples of coupling agents include metal halides,metalloid halides, alkoxysilanes, alkoxystannanes, and combinationsthereof.

In one or more embodiments of the first-fourth embodiments, the couplingagent for the styrene-butadiene rubber of (i) comprises a metal halideor metalloid halide selected from the group comprising compoundsexpressed by the formula (1) R*_(n)M¹Y_((4-n)), the formula (2) M¹Y₄,and the formula (3) M²Y₃, where each R* is independently a monovalentorganic group having 1 to 20 carbon atoms, M¹ is a tin atom, siliconatom, or germanium atom, M² is a phosphorous atom, Y is a halogen atom,and n is an integer of 0-3.

Exemplary compounds expressed by the formula (1) include halogenatedorganic metal compounds, and the compounds expressed by the formulas (2)and (3) include halogenated metal compounds.

In the case where M¹ represents a tin atom, the compounds expressed bythe formula (1) can be, for example, triphenyltin chloride, tributyltinchloride, triisopropyltin chloride, trihexyltin chloride, trioctyltinchloride, diphenyltin dichloride, dibutyltin dichloride, dihexyltindichloride, dioctyltin dichloride, phenyltin trichloride, butyltintrichloride, octyltin trichloride and the like. Furthermore, tintetrachloride, tin tetrabromide and the like can be exemplified as thecompounds expressed by formula (2).

In the case where M¹ represents a silicon atom, the compounds expressedby the formula (1) can be, for example, triphenylchlorosilane,trihexylchlorosilane, trioctylchlorosilane, tributylchlorosilane,trimethylchlorosilane, diphenyldichlorosilane, dihexyldichlorosilane,dioctyldichlorosilane, dibutyldichlorosilane, dimethyldichlorosilane,methyltrichlorosilane, phenyltrichlorosilane, hexyltrichlorosilane,octyltrichlorosilane, butyltrichlorosilane, methyltrichlorosilane andthe like. Furthermore, silicon tetrachloride, silicon tetrabromide andthe like can be exemplified as the compounds expressed by the formula(2). In the case where M¹ represents a germanium atom, the compoundsexpressed by the formula (1) can be, for example, triphenylgermaniumchloride, dibutylgermanium dichloride, diphenylgermanium dichloride,butylgermanium trichloride and the like. Furthermore, germaniumtetrachloride, germanium tetrabromide and the like can be exemplified asthe compounds expressed by the formula (2). Phosphorous trichloride,phosphorous tribromide and the like can be exemplified as the compoundsexpressed by the formula (3). In one or more embodiments, mixtures ofmetal halides and/or metalloid halides can be used.

In one or more embodiments of the first-fourth embodiments, the couplingagent for the styrene-butadiene rubber of (i) comprises an alkoxysilaneor alkoxystannane selected from the group comprising compounds expressedby the formula (4) R*_(n)M¹(OR{circumflex over ( )})_(4-n), where eachR* is independently a monovalent organic group having 1 to 20 carbonatoms, M¹ is a tin atom, silicon atom, or germanium atom, OR{circumflexover ( )} is an alkoxy group where R{circumflex over ( )} is amonovalent organic group, and n is an integer of 0-3.

Exemplary compounds expressed by the formula (4) include tetraethylorthosilicate, tetramethyl orthosilicate, tetrapropyl orthosilicate,tetraethoxy tin, tetramethoxytin, and tetrapropoxytin.

According to the first-fourth embodiments disclosed herein, the Mw, Mnand polydispersity (Mw/Mn) of the one or more styrene-butadiene rubbershaving a silica-reactive functional group (i.e., the styrene-butadienerubber(s) of (i)) may vary. As mentioned above, according to the thirdembodiment, the two styrene-butadiene rubbers having a silica-reactivefunction group, each having a Tg of about −v65 to about −40 C., have aMw of 250,000 to 600,000 grams/mole. In certain embodiments of thefirst-fourth embodiments, the styrene-butadiene rubber(s) of (i) have asilica-reactive functional group have a Mw of 300,000 to 600,000grams/mole (e.g., 300,000; 325,000; 350,000; 375,000; 400,000; 425,000;450,000; 475,000; 500,000; 525,000; 550,000; 575,000; or 600,000grams/mole). In certain embodiments of the first-fourth embodiments, thestyrene-butadiene rubber(s) of (i) have a Mw of 250,000 to 600,000;300,000 to 600,000; 350,000 to 550,000, or 400,000 to 500,000grams/mole. The Mw values referred to herein are weight averagemolecular weights which can be determined by using gel permeationchromatography (GPC) calibrated with styrene-butadiene standards andMark-Houwink constants for the polymer in question. In certainembodiments of the first-fourth embodiments, the styrene-butadienerubber(s) of (i) have a Mn of 200,000 to 400,000 grams/mole (e.g.,200,000; 225,000; 250,000; 275,000; 300,000; 325,000; 350,000; 375,000;or 400,000 grams/mole). In certain embodiments of the first-fourthembodiments, the styrene-butadiene rubber(s) of (i) have a Mn of 200,000to 350,000, or 200,000 to 300,000 grams/mole. The Mn values referred toherein are number average molecular weights which can be determined byusing gel permeation chromatography (GPC) calibrated withstyrene-butadiene standards and Mark-Houwink constants for the polymerin question. In certain embodiments of the first-fourth embodimentsdisclosed herein, In certain embodiments of the first-fourth embodimentsdisclosed herein, the styrene-butadiene rubber(s) of (i) has(have) aMw/Mn (polydispersity) of 1.2 to 2.5 to (e.g., 1.2, 1.3, 1.4, 1.5, 1.6,1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, or 2.5), preferably 1.3 to 2, or1.3 to 1.6.

As mentioned above, according to the first embodiment 10-55 parts (e.g.,10, 15, 20, 25, 30, 35, 40, 45, 49, or 50 parts) and according to thesecond and third embodiments 10-50 parts (e.g., 10, 15, 20, 25, 30, 35,40, 44, or 45 parts) of natural rubber, polyisoprene, or a combinationthereof are present as (ii) in the tread rubber composition. In certainembodiments of the first-fourth embodiment, (ii) consists (only) ofnatural rubber. In other embodiments of the first-fourth embodiment,(ii) consists (only) of polyisoprene. When natural rubber is present, itmay include Hevea natural rubber, non-Hevea natural rubber (e.g.,guayule natural rubber), or a combination thereof. When natural rubberis utilized in the tread rubber compositions of the first-fourthembodiments, the natural rubber preferably has a Mw of 1,000,000 to2,000,000 grams/mole (e.g., 1 million, 1.1 million, 1.2 million, 1.3million, 1.4 million, 1.5 million, 1.6 million, 1.7 million, 1.8million, 1.9 million, 2 million grams/mole); 1,250,000 to 2,000,000grams/mole, or 1,500,000 to 2,000,000 grams/mole (as measured by GPCusing a polystyrene standard). In certain preferred embodiments of thefirst-fourth embodiments, the natural rubber and/or polyisoprene of (ii)is non-epoxidized; in certain such embodiments, the tread rubbercomposition contains no more than 10 phr of epoxidized natural rubber orepoxidized polyisoprene, preferably no more than 5 phr of epoxidizednatural rubber or epoxidized polyisoprene, more preferably 0 phr ofepoxidized natural rubber or epoxidized polyisoprene.

As mentioned above, in certain embodiments of the first-fourthembodiments, polybutadiene rubber may be present in the tread rubbercomposition as an additional rubber. When polybutadiene rubber ispresent, it preferably has a cis 1,4-bond content of at least 95% (e.g.,95%, 96%, 97%, 98%, 99%, or more), or even at least 98% (e.g., 98%, 99%,or more), or at least 99% (e.g., 99%, 99.5%, or more). The cis bondcontent refers to the cis 1,4-bond content. In certain embodiments ofthe first-fourth embodiments, any polybutadiene rubber used in the treadrubber compositions has a Tg of less than −101° C. (e.g., −102, −103,−104, −105, −106, −107, −108, −109° C. or less), or a Tg of −101 to−110° C., −105 to −110° C., or −105 to −108° C. In certain embodimentsof the first-fourth embodiments, any polybutadiene rubber used in thetread rubber compositions has a Tg of −105° C. or less (e.g., −105,−106, −107, −108, −109° C. or less). In certain embodiments of thefirst-fourth embodiments, any polybutadiene rubber used in the treadrubber compositions contains less than 3% by weight (e.g., 3%, 2%, 1%,0.5%, or less), preferably less than 1% by weight (e.g., 1%, 0.5%, orless) or 0% by weight syndiotactic 1,2-polybutadiene. Generally,according to the first-fourth embodiments, when a polybutadiene rubberis used in the tread rubber compositions, one or more than onepolybutadiene rubber having a cis bond content of at least 95% (e.g.,95%, 96%, 97%, 98%, 99%, or more) and a Tg of less than −101° C. may beused. In certain embodiments of the first-fourth embodiments, only onepolybutadiene rubber having a cis bond content of at least 95% (e.g.,95%, 96%, 97%, 98%, 99%, or more) and a Tg of less than −101° C. is usedin the tread rubber composition.

Fillers

As used herein, the term “reinforcing” with respect to “reinforcingcarbon black filler,” “reinforcing silica filler,” and “reinforcingfiller” generally should be understood to encompass both fillers thatare traditionally described as reinforcing as well as fillers that maytraditionally be described as semi-reinforcing. Traditionally, the term“reinforcing filler” is used to refer to a particulate material that hasa nitrogen absorption specific surface area (N₂SA) of more than about100 m²/g, and in certain instances more than 100 m²/g, more than about125 m²/g, more than 125 m²/g, or even more than about 150 m²/g or morethan 150 m²/g. Alternatively (or additionally), the traditional use ofthe term “reinforcing filler” can also be used to refer to a particulatematerial that has a particle size of about 10 nm to about 50 nm(including 10 nm to 50 nm). Traditionally, the term “semi-reinforcingfiller” is used to refer to a filler that is intermediary in eitherparticle size, surface area (N₂SA), or both, to a non-reinforcing filler(as discussed below) and a reinforcing filler. In certain embodiments ofthe first-fourth embodiments disclosed herein, the term “reinforcingfiller” is used to refer to a particulate material that has a nitrogenabsorption specific surface area (N₂SA) of about 20 m²/g or greater,including 20 m²/g or greater, more than about 50 m²/g, more than 50m²/g, more than about 100 m²/g, more than 100 m²/g , more than about 125m²/g, and more than 125 m²/g. In certain embodiments of the first-fourthembodiments disclosed herein, the term “reinforcing filler” is used torefer to a particulate material that has a particle size of about 10 nmup to about 1000 nm, including 10 nm to 1000 nm, about 10 nm up to about50 nm and 10 nm to 50 nm.

Reinforcing Silica Filler

As mentioned above, according to the first embodiment, the tread rubbercomposition comprises (includes) at least one reinforcing silica fillerin an amount of 50-150 phr (e.g., 50, 51, 55, 59, 60, 61, 65, 69, 70,71, 75, 79, 80, 81, 85, 89, 90, 91, 95, 99, 100, 101, 105, 109, 110,111, 115, 119, 120, 121, 125, 129, 130, 131, 135, 139, 140, 141, 145,149, or 150 phr). In certain embodiments of the first embodiment, theamount of reinforcing silica filler is 50-89 phr (e.g., 50, 51, 55, 59,60, 61, 65, 69, 70, 71, 75, 79, 80, 81, 85, or 89 phr). As alsomentioned above, according to the second and third embodiments, thetread rubber composition comprises (includes) at least one reinforcingsilica filler in an amount of 50-89 phr (e.g., 50, 51, 55, 59, 60, 61,65, 69, 70, 71, 75, 79, 80, 81, 85, or 89 phr). In certain embodimentsof the first-fourth embodiments, the tread rubber composition comprises(includes) at least one reinforcing silica filler in an amount of 55-75phr. According to the first-fourth embodiments, one or more than onereinforcing silica filler may be utilized; in those embodiments wheremore than one reinforcing silica filler is utilized, the foregoingamounts refer to the total amount of all reinforcing silica fillers. Incertain embodiments of the first-fourth embodiments, only onereinforcing silica filler is utilized.

According to the first-fourth embodiments, the particular type of silicafor the at least one reinforcing silica filler may vary. Non-limitingexamples of reinforcing silica fillers suitable for use in certainembodiments of the first-fourth embodiments include, but are not limitedto, precipitated amorphous silica, wet silica (hydrated silicic acid),dry silica (anhydrous silicic acid), fumed silica, calcium silicate andthe like. Other suitable reinforcing silica fillers for use in certainembodiments of the first-fourth embodiments include, but are not limitedto, aluminum silicate, magnesium silicate (Mg₂SiO₄, MgSiO₃ etc.),magnesium calcium silicate (CaMgSiO₄), calcium silicate (Ca2SiO₄ etc.),aluminum silicate (Al₂SiO₅, Al_(4.3)SiO₄.5H₂O etc.), aluminum calciumsilicate (Al₂O₃. CaO₂SiO₂, etc.), and the like. Among the listedreinforcing silica fillers, precipitated amorphous wet-process, hydratedsilica fillers are preferred. Such reinforcing silica fillers areproduced by a chemical reaction in water, from which they areprecipitated as ultrafine, spherical particles, with primary particlesstrongly associated into aggregates, which in turn combine less stronglyinto agglomerates. The surface area, as measured by the BET method, is apreferred measurement for characterizing the reinforcing character ofdifferent reinforcing silica fillers. In certain embodiments of thefirst-fourth embodiments disclosed herein, the rubber compositioncomprises a reinforcing silica filler having a surface area (as measuredby the BET method) of about 100 m²/g to about 400 m²/g, 100 m²/g to 400m²/g, about 100 m²/g to about 350 m²/g, or 100 m²/g to 350 m²/g. Incertain embodiments of the first-fourth embodiments disclosed herein,the rubber composition comprises a reinforcing silica filler having aBET surface area of about 150 m²/g to about 400 m²/g, 150 m²/g to 400m²/g (e.g., 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260,270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, or 400m²/g), with the ranges of about 170 m²/g to about 350 m²/g, 170 m²/g to350 m²/g (e.g., 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270,280, 290, 300, 310, 320, 330, 340, or 350 m²/g), about 170 m²/g to about320 m²/g, and 170 m²/g to 320 m²/g (e.g., 170, 180, 190, 200, 210, 220,230, 240, 250, 260, 270, 280, 290, 300, 310, or 320 m²/g) beingincluded; in certain such embodiments the only silica filler present inthe rubber composition has a BET surface area within one of theforegoing ranges. In other embodiments of the first-fourth embodimentsdisclosed herein, the rubber composition comprises a reinforcing silicafiller having a BET surface of about 100 m²/g to about 140 m²/g, 100m²/g to 140 m²/g (e.g., 100, 105, 110, 115, 120, 125, 130, 135, or 140m²/g), about 100 m²/g to about 125 m²/g, 100 m²/g to 125 m²/g (e.g.,100, 105, 110, 115, 120, or 125 m²/g), about 100 m²/g to about 120 m²/g,or 100 to 120 m²/g (e.g., 100, 105, 110, 115, or 120 m²/g); in certainsuch embodiments the only silica filler present in the rubbercomposition has a BET surface area within one of the foregoing ranges.In certain embodiments of the first-fourth embodiments disclosed herein,the rubber composition comprises reinforcing silica filler having a pHof about 5.5 to about 8, 5.5 to 8 (e.g., 5.5, 5.7, 5.9, 6.1, 6.3, 6.5,6.7, 6.9, 7.1, 7.3, 7.5, 7.7, 7.9, or 8), about 6 to about 8, 6 to 8(e.g., 6, 6.2, 6.4, 6.6, 6.8, 7, 7.2, 7.4, 7.6, 7.8, or 8), about 6 toabout 7.5, 6 to 7.5, about 6.5 to about 8, 6.5 to 8, about 6.5 to about7.5, 6.5 to 7.5, about 5.5 to about 6.8, or 5.5 to 6.8. Some of thecommercially available reinforcing silica fillers which can be used incertain embodiments of the first-fourth embodiments include, but are notlimited to, Hi-Sil® EZ120G, Hi-Sil® EZ120G-D, Hi-Sil® 134G, Hi-Sil® EZ160G, Hi-Sil® EZ 160G-D, Hi-Sil® 190, Hi-Sil® 190G-D, Hi-Sil® EZ 200G,Hi-Sil® EZ 200G-D, Hi-Sil® 210, Hi-Sil® 233, Hi-Sil® 243LD, Hi-Sil®255CG-D, Hi-Sil® 315-D, Hi-Sil® 315G-D, Hi-Sil® HDP 320G and the like,produced by PPG Industries (Pittsburgh, Pa.) As well, a number of usefulcommercial grades of different reinforcing silica fillers are alsoavailable from Evonik Corporation (e.g., Ultrasil® 320 GR, Ultrasil®5000 GR, Ultrasil® 5500 GR, Ultrasil® 7000 GR, Ultrasil® VN2 GR,Ultrasil® VN2, Ultrasil® VN3, Ultrasil® VN3 GR, Ultrasil® 7000 GR,Ultrasil® 7005, Ultrasil® 7500 GR, Ultrasil® 7800 GR, Ultrasil® 9500 GR,Ultrasil® 9000 G, Ultrasil® 9100 GR), and Solvay (e.g., Zeosil® 1115MP,Zeosil® 1085GR, Zeosil® 1165MP, Zeosil® 1200MP, Zeosil® Premium, Zeosil®195HR, Zeosil® 195GR, Zeosil® 185GR, Zeosil® 175GR, and Zeosil® 165 GR).

In certain embodiments of the first-fourth embodiments disclosed herein,one or more than one silica coupling agent may also (optionally) beutilized. Silica coupling agents are useful in preventing or reducingaggregation of the silica filler in rubber compositions. Aggregates ofthe silica filler particles are believed to increase the viscosity of arubber composition, and, therefore, preventing this aggregation reducesthe viscosity and improves the processability and blending of the rubbercomposition.

Generally, any conventional type of silica coupling agent can be used,such as those having a silane and a constituent component or moiety thatcan react with a polymer, particularly a vulcanizable polymer. Thesilica coupling agent acts as a connecting bridge between silica and thepolymer. Suitable silica coupling agents for use in certain embodimentsof the first-fourth embodiments disclosed herein include thosecontaining groups such as alkyl alkoxy, mercapto, blocked mercapto,sulfide-containing (e.g., monosulfide-based alkoxy-containing,disulfide-based alkoxy-containing, tetrasulfide-basedalkoxy-containing), amino, vinyl, epoxy, and combinations thereof. Incertain embodiments, the silica coupling agent can be added to therubber composition in the form of a pre-treated silica; a pre-treatedsilica has been pre-surface treated with a silane prior to being addedto the rubber composition. The use of a pre-treated silica can allow fortwo ingredients (i.e., silica and a silica coupling agent) to be addedin one ingredient, which generally tends to make rubber compoundingeasier.

Alkyl alkoxysilanes have the general formula R¹⁰ _(p) Si(OR¹¹)_(4-p)where each R¹¹ is independently a monovalent organic group, and p is aninteger from 1 to 3, with the proviso that at least one R¹⁰ is an alkylgroup. Preferably p is 1. Generally, each R¹⁰ independently comprises C₁to C₂₀ aliphatic, C₅ to C₂₀ cycloaliphatic, or C₆ to C₂₀ aromatic; andeach R¹¹ independently comprises C₁ to C₆ aliphatic. In certainexemplary embodiments, each R¹⁰ independently comprises C₆ to C₁₅aliphatic and in additional embodiments each R¹⁰ independently comprisesC₈ to C₁₄ aliphatic. Mercapto silanes have the general formulaHS—R¹³—Si(R¹⁴)(R¹⁵)₂ where R¹³ is a divalent organic group, R¹⁴ is ahalogen atom or an alkoxy group, each R¹⁵ is independently a halogen, analkoxy group or a monovalent organic group. The halogen is chlorine,bromine, fluorine, or iodine. The alkoxy group preferably has 1-3 carbonatoms. Blocked mercapto silanes have the general formula B—S—R¹⁶—Si—₃with an available silyl group for reaction with silica in asilica-silane reaction and a blocking group B that replaces the mercaptohydrogen atom to block the reaction of the sulfur atom with the polymer.In the foregoing general formula, B is a block group which can be in theform of an unsaturated heteroatom or carbon bound directly to sulfur viaa single bond; R¹⁶ is C₁ to C₆ linear or branched alkylidene and each Xis independently selected from the group consisting of C₁ to C₄ alkyl orC₁ to C₄ alkoxy.

Non-limiting examples of alkyl alkoxysilanes suitable for use in certainembodiments of the first-fourth embodiments include, but are not limitedto, octyltriethoxysilane, octyltrimethoxysilane, trimethylethoxysilane,cyclohexyltriethoxysilane, isobutyltriethoxysilane,ethyltrimethoxysilane, cyclohexyltributoxysilane,dimethyldiethoxysilane, methyltriethoxysilane, propyltriethoxysilane,hexyltriethoxysilane, heptyltriethoxysilane, nonyltriethoxysilane,decyltriethoxysilane, dodecyltriethoxysilane, tetradecyltriethoxysilane,octadecyltriethoxysilane, methyloctyldiethoxysilane,dimethyldimethoxysilane, methyltrimethoxysilane, propyltrimethoxysilane,hexyltrimethoxysilane, heptyltrimethoxysilane, nonyltrimethoxysilane,decyltrimethoxysilane, dodecyltrimethoxysilane,tetradecyltrimethoxysilane, octadecyl-trimethoxysilane, methyloctyldimethoxysilane, and mixtures thereof.

Non-limiting examples of bis(trialkoxysilylorgano)polysulfides suitablefor use in certain embodiments of the first-fourth embodiments includebis(trialkoxysilylorgano) disulfides andbis(trialkoxysilylorgano)tetrasulfides. Specific non-limiting examplesof bis(trialkoxysilylorgano)disulfides include, but are not limited to,3,3′-bis(triethoxysilylpropyl) disulfide,3,3′-bis(trimethoxysilylpropyl)disulfide,3,3′-bis(tributoxysilylpropyl)disulfide,3,3′-bis(tri-t-butoxysilylpropyl)disulfide,3,3′-bis(trihexoxysilylpropyl)disulfide,2,2′-bis(dimethylmethoxysilylethyl)disulfide,3,3′-bis(diphenylcyclohexoxysilylpropyl)disulfide,3,3′-bis(ethyl-di-sec-butoxysilylpropyl)disulfide,3,3′-bis(propyldiethoxysilylpropyl)disulfide,12,12′-bis(triisopropoxysilylpropyl)disulfide,3,3′-bis(dimethoxyphenylsilyl-2-methylpropyl)disulfide, and mixturesthereof. Non-limiting examples of bis(trialkoxysilylorgano)tetrasulfidesilica coupling agents suitable for use in certain embodiments of thefirst-fourth embodiments include, but are not limited to,bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasufide, bis(3-trimethoxysilylpropyl)tetrasulfide,3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide,3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide,2-triethoxysilyl-N,N-dimethylthiocarbamoyl tetrasulfide,3-trimethoxysilylpropyl-benzothiazoletetrasulfide,3-triethoxysilylpropylbenzothiazole tetrasulfide, and mixtures thereof.Bis(3-triethoxysilylpropyl)tetrasulfide is sold commercially as Si69® byEvonik Degussa Corporation.

Non-limiting examples of mercapto silanes suitable for use in certainembodiments of first-fourth embodiments disclosed herein include, butare not limited to, 1-mercaptomethyltriethoxysilane,2-mercaptoethyltriethoxysilane, 3-mercaptopropyltriethoxysilane,3-mercaptopropylmethyldiethoxysilane, 2-mercaptoethyltripropoxysilane,18-mercaptooctadecyldiethoxychlorosilane, and mixtures thereof.

Non-limiting examples of blocked mercapto silanes suitable for use incertain embodiments of the first-fourth embodiments disclosed hereininclude, but are not limited to, those described in U.S. Pat. Nos.6,127,468; 6,204,339; 6,528,673; 6,635,700; 6,649,684; and 6,683,135,the disclosures of which are hereby incorporated by reference.Representative examples of the blocked mercapto silanes include, but arenot limited to, 2-triethoxysilyl-1-ethylthioacetate;2-trimethoxysilyl-1-ethylthioacetate;2-(methyldimethoxysilyl)-1-ethylthioacetate;3-trimethoxysilyl-1-propylthioacetate; triethoxysilylmethyl-thioacetate;trimethoxysilylmethylthioacetate; triisopropoxysilylmethylthioacetate;methyldiethoxysilylmethylthioacetate;methyldimethoxysilylmethylthioacetate;methyldiisopropoxysilylmethylthioacetate;dimethylethoxysilylmethylthioacetate;dimethylmethoxysilylmethylthioacetate;dimethylisopropoxysilylmethylthioacetate;2-triisopropoxysilyl-1-ethylthioacetate;2-(methyldiethoxysilyl)-1-ethylthioacetate,2-(methyldiisopropoxysilyl)-1-ethylthioacetate;2-(dimethylethoxysilyl-1-ethylthioacetate;2-(dimethylmethoxysilyl)-1-ethylthioacetate;2-(dimethylisopropoxysilyl)-1-ethylthioacetate;3-triethoxysilyl-1-propylthioacetate;3-triisopropoxysilyl-1-propylthioacetate;3-methyldiethoxysilyl-1-propylthioacetate;3-methyldimethoxysilyl-1-propylthioacetate;3-methyldiisopropoxysilyl-1-propylthioacetate;1-(2-triethoxysilyl-1-ethyl)-4-thioacetylcyclohexane;1-(2-triethoxysilyl-1-ethyl)-3-thioacetylcyclohexane;2-triethoxysilyl-5-thioacetylnorbornene;2-triethoxysilyl-4-thioacetylnorbornene;2-(2-triethoxysilyl-1-ethyl)-5-thioacetylnorbornene;2-(2-triethoxy-silyl-1-ethyl)-4-thioacetylnorbornene;1-(1-oxo-2-thia-5-triethoxysilylphenyl)benzoic acid;6-triethoxysilyl-1-hexylthioacetate;1-triethoxysilyl-5-hexylthioacetate;8-triethoxysilyl-1-octylthioacetate;1-triethoxysilyl-7-octylthioacetate;6-triethoxysilyl-1-hexylthioacetate;1-triethoxysilyl-5-octylthioacetate;8-trimethoxysilyl-1-octylthioacetate;1-trimethoxysilyl-7-octylthioacetate;10-triethoxysilyl-1-decylthioacetate;1-triethoxysilyl-9-decylthioacetate;1-triethoxysilyl-2-butylthioacetate;1-triethoxysilyl-3-butylthioacetate;1-triethoxysilyl-3-methyl-2-butylthioacetate;1-triethoxysilyl-3-methyl-3-butylthioacetate;3-trimethoxysilyl-1-propylthiooctanoate;3-triethoxysilyl-1-propyl-1-propylthiopalmitate;3-triethoxysilyl-1-propylthiooctanoate;3-triethoxysilyl-1-propylthiobenzoate;3-triethoxysilyl-1-propylthio-2-ethylhexanoate;3-methyldiacetoxysilyl-1-propylthioacetate;3-triacetoxysilyl-1-propylthioacetate;2-methyldiacetoxysilyl-1-ethylthioacetate;2-triacetoxysilyl-1-ethylthioacetate;1-methyldiacetoxysilyl-1-ethylthioacetate;1-triacetoxysilyl-1-ethyl-thioacetate;tris-(3-triethoxysilyl-1-propyl)trithiophosphate;bis-(3-triethoxysilyl-1-propyl)methyldithiophosphonate;bis-(3-triethoxysilyl-1-propyl)ethyldithiophosphonate;3-triethoxysilyl-1-propyldimethylthiophosphinate;3-triethoxysilyl-1-propyldiethylthiophosphinate;tris-(3-triethoxysilyl-1-propyl)tetrathiophosphate;bis-(3-triethoxysilyl-1 propyl)methyltrithiophosphonate;bis-(3-triethoxysilyl-1-propyl)ethyltrithiophosphonate;3-triethoxysilyl-1-propyldimethyldithiophosphinate;3-triethoxysilyl-1-propyldiethyldithiophosphinate;tris-(3-methyldimethoxysilyl-1-propyl)trithiophosphate;bis-(3-methyldimethoxysilyl-1-propyl)methyldithiophosphonate;bis-(3-methyldimethoxysilyl-1-propyl)-ethyldithiophosphonate;3-methyldimethoxysilyl-1-propyldimethylthiophosphinate;3-methyldimethoxysilyl-1-propyldiethylthiophosphinate;3-triethoxysilyl-1-propylmethylthiosulfate;3-triethoxysilyl-1-propylmethanethiosulfonate;3-triethoxysilyl-1-propylethanethiosulfonate;3-triethoxysilyl-1-propylbenzenethiosulfonate;3-triethoxysilyl-1-propyltoluenethiosulfonate;3-triethoxysilyl-1-propylnaphthalenethiosulfonate;3-triethoxysilyl-1-propylxylenethiosulfonate; triethoxysilyl methylmethylthiosulfate; triethoxysilylmethylmethanethiosulfonate;triethoxysilylmethylethanethiosulfonate;triethoxysilylmethylbenzenethiosulfonate;triethoxysilylmethyltoluenethiosulfonate;triethoxysilylmethylnaphthalenethiosulfonate;triethoxysilylmethylxylenethiosulfonate, and the like. Mixtures ofvarious blocked mercapto silanes can be used. A further example of asuitable blocked mercapto silane for use in certain exemplaryembodiments is NXT™ silane (3-octanoylthio-1-propyltriethoxysilane),commercially available from Momentive Performance Materials Inc. ofAlbany, N.Y.

Non-limiting examples of pre-treated silicas (i.e., silicas that havebeen pre-surface treated with a silane) suitable for use in certainembodiments of the first-fourth embodiments disclosed herein include,but are not limited to, Ciptane® 255 LD and Ciptane® LP (PPG Industries)silicas that have been pre-treated with a mercaptosilane, and Coupsil®8113 (Degussa) that is the product of the reaction between organosilanebis(triethoxysilylpropyl) polysulfide (Si69) and Ultrasil® VN3 silica.Coupsil 6508, Agilon 400™ silica from PPG Industries, Agilon 454® silicafrom PPG Industries, and 458® silica from PPG Industries. In thoseembodiments where the silica comprises a pre-treated silica, thepre-treated silica is used in an amount as previously disclosed for thesilica filler (i.e., about 5 to about 200 phr, etc.).

When a silica coupling agent is utilized in an embodiment of thefirst-fourth embodiments, the amount used may vary. In certainembodiments of the first-fourth embodiments, the rubber compositions donot contain any silica coupling agent. In other embodiments of thefirst-fourth embodiments, the silica coupling agent is present in anamount sufficient to provide a ratio of the total amount of silicacoupling agent to silica filler of about 0.1:100 to about 1:5 (i.e.,about 0.1 to about 20 parts by weight per 100 parts of silica),including 0.1:100 to 1:5, about 1:100 to about 1:10, 1:100 to 1:10,about 1:100 to about 1:20, 1:100 to 1:20, about 1:100 to about 1:25, and1:100 to 1:25 as well as about 1:100 to about 0:100 and 1:100 to 0:100.In certain embodiments according to the first-fourth embodiments, therubber composition comprises about 0.1 to about 15 phr silica couplingagent, including 0.1 to 15 phr (e.g., 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8,9, 10, 11, 12, 13, 14, or 15 phr), about 0.1 to about 12 phr, 0.1 to 12phr, about 0.1 to about 10 phr, 0.1 to 10 phr, about 0.1 to about 7 phr,0.1 to 7 phr, about 0.1 to about 5 phr, 0.1 to 5 phr, about 0.1 to about3 phr, 0.1 to 3 phr, about 1 to about 15 phr, 1 to 15 phr (e.g., 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 phr), about 1 to about 12phr, 1 to 12 phr (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 phr),about 1 to about 10 phr, 1 to 10 phr (e.g., 1, 1.5, 2, 2.5, 3, 3.5, 4,4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or 10 phr), about 1 toabout 7 phr, 1 to 7 phr, about 1 to about 5 phr, 1 to 5 phr, about 1 toabout 3 phr, 1 to 3 phr, about 3 to about 15 phr, 3 to 15 phr, about 3to about 12 phr, 3 to 12 phr, about 3 to about 10 phr, 3 to 10 phr,about 3 to about 7 phr, 3 to 7 phr, about 3 to about 5 phr, 3 to 5 phr,about 5 to about 15 phr, 5 to 15 phr, about 5 to about 12 phr, 5 to 12phr, about 5 to about 10 phr, 5 to 10 phr, about 5 to about 7 phr, or 5to 7 phr.

Carbon Black Filler

In certain preferred embodiments of the first embodiment, the treadrubber composition contains a limited amount (if any) of carbon blackfiller; in certain such embodiments, the tread rubber compositioncontains no more than 20 phr of carbon black filler (e.g., 20, 19, 18,17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 or even 0phr), no more than 10 phr (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or even0 phr) of carbon black filler, or no more than 5 phr (e.g., 5, 4, 3, 2,1 or even 0 phr) of carbon black filler. As mentioned above according tothe second and third embodiments, the tread rubber composition containsno more than 20 phr of carbon black filler (e.g., 20, 19, 18, 17, 16,15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 or even 0 phr). Incertain embodiments of the second and third embodiments, the amount ofcarbon black filler is even more limited such as no more than 10 phr(e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or even 0 phr) of carbon blackfiller, or no more than 5 phr (e.g., 5, 4, 3, 2, 1 or even 0 phr). Incertain embodiments of the first-fourth embodiments, the tread rubbercomposition contains 0 phr of carbon black filler. In certainembodiments of the first-fourth embodiments, the foregoing limitedamounts of carbon black filler should be understood to refer toreinforcing carbon black filler. In other embodiments of thefirst-fourth embodiments, the foregoing limited amounts of carbon blackfiller should be understood to refer to non-reinforcing carbon blackfiller. In yet other embodiments of the first-fourth embodiments, theforegoing limited amounts of carbon black filler should be understood torefer to all forms of carbon black (i.e., both reinforcing andnon-reinforcing carbon black filler).

In those embodiments of the first-fourth embodiments where carbon blackfiller is present, the particular type or types of carbon black utilizedmay vary. Generally, suitable carbon blacks for use as a reinforcingfiller in the rubber composition of certain embodiments of thefirst-fourth embodiments include any of the commonly available,commercially-produced carbon blacks, including those having a surfacearea of at least about 20 m²/g (including at least 20 m²/g) and, morepreferably, at least about 35 m²/g up to about 200 m²/g or higher(including 35 m²/g up to 200 m²/g). Surface area values used herein forcarbon blacks are determined by ASTM D-1765 using thecetyltrimethyl-ammonium bromide (CTAB) technique. Among the usefulcarbon blacks are furnace black, channel blacks, and lamp blacks. Morespecifically, examples of useful carbon blacks include super abrasionfurnace (SAF) blacks, high abrasion furnace (HAF) blacks, fast extrusionfurnace (FEF) blacks, fine furnace (FF) blacks, intermediate superabrasion furnace (ISAF) blacks, semi-reinforcing furnace (SRF) blacks,medium processing channel blacks, hard processing channel blacks andconducting channel blacks. Other carbon blacks which can be utilizedinclude acetylene blacks. In certain embodiments of the first-fourthembodiments, the rubber composition includes a mixture of two or more ofthe foregoing blacks. Preferably according to the first-fourthembodiments, if a carbon black filler is present it consists of only onetype (or grade) of reinforcing carbon black. Typical suitable carbonblacks for use in certain p P18013US3A embodiments of the first-fourthembodiments are N-110, N-220, N-339, N-330, N-351, N-550, and N-660, asdesignated by ASTM D-1765-82a. The carbon blacks utilized can be inpelletized form or an unpelletized flocculent mass. Preferably, for moreuniform mixing, unpelletized carbon black is preferred.

Other Reinforcing Fillers

In certain embodiments of the first-fourth embodiments, the tread rubbercomposition comprises a reinforcing filler other than carbon black orsilica (i.e., an additional reinforcing filler). While one or more thanone additional reinforcing filler may be utilized, their total amount ispreferably limited to no more than 10 phr (e.g., 10, 9, 8, 7, 6, 5, 4,3, 2, 1 or 0 phr), or no more than 5 phr (e.g., 5, 4, 3, 2, 1, or 0phr). In certain embodiments of the first-fourth embodiments, the treadrubber composition contains no additional reinforcing filler (i.e., 0phr); in other words, in such embodiments no reinforcing filler otherthan silica and optionally carbon black are present.

In those embodiments of the first-fourth embodiments wherein anadditional reinforcing filler is utilized, the additional reinforcingfiller or fillers may vary. Non-limiting examples of suitable additionalreinforcing fillers for use in the tread rubber compositions of certainembodiments of the first-fourth embodiments include, but are not limitedto, alumina, aluminum hydroxide, clay (reinforcing grades), magnesiumhydroxide, boron nitride, aluminum nitride, titanium dioxide,reinforcing zinc oxide, and combinations thereof.

Non-Reinforcing Fillers

In certain embodiments of the first-fourth embodiments, the tread rubbercomposition further comprises at least one non-reinforcing filler. Inother embodiments of the first-fourth embodiments, the tread rubbercomposition contains no non-reinforcing fillers (i.e., 0 phr). Inembodiments of the first-fourth embodiments wherein at least onenon-reinforcing filler is utilized, the at least one non-reinforcingfiller may be selected from clay (non-reinforcing grades), graphite,magnesium dioxide, aluminum oxide, starch, boron nitride(non-reinforcing grades), silicon nitride, aluminum nitride(non-reinforcing grades), calcium silicate, silicon carbide, groundrubber, and combinations thereof. The term “non-reinforcing filler” isused to refer to a particulate material that has a nitrogen absorptionspecific surface area (N₂SA) of less than about 20 m²/g (including lessthan 20 m²/g), and in certain embodiments less than about 10 m²/g(including less than 10 m²/g). The N2SA surface area of a particulatematerial can be determined according to various standard methodsincluding ASTM D6556. In certain embodiments, the term “non-reinforcingfiller” is alternatively or additionally used to refer to a particulatematerial that has a particle size of greater than about 1000 nm(including greater than 1000 nm). In those embodiments of thefirst-fourth embodiments, wherein a non-reinforcing filler is present inthe rubber composition, the total amount of non-reinforcing filler mayvary but is preferably no more than 10 phr (e.g., 10, 9, 8, 7, 6, 5, 4,3, 2, or 1 phr), and in certain embodiments 1-10 phr, no more than 5 phr(e.g., 5, 4, 3, 2, or 1 phr), 1-5 phr, or no more than 1 phr.

Hydrocarbon Resins

As mentioned above, according to the first-fourth embodiments, the treadrubber composition comprises (includes) 11-40 phr (e.g., 11, 12, 13, 14,15, 20, 25, 30, 35, or 40 phr) of at least one hydrocarbon resin havinga Tg of about 35 to about 60° C., or 35-60° C. (e.g., 35, 36, 38, 40,42, 44, 45, 46, 48, 50, 52, 54, 55, 56, 58, or 60° C.). Hydrocarbonresin Tg can be determined by DSC, according to the procedure discussedabove for elastomer Tg measurements. In certain embodiments of thefirst-fourth embodiments, the tread rubber composition includes 11-30phr (e.g., 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,26, 27, 28, 29 or 30 phr), 15-30 phr (e.g., 15, 16, 17, 18, 19, 20, 21,22, 23, 24, 25, 26, 27, 28, 29 or 30 phr), 11-25 phr (e.g., 11, 12, 13,14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 phr), or 15-25 phr(e.g., 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 phr) of at leastone hydrocarbon resin having a Tg of about 35 to about 60° C. or 35-60°C. In certain embodiments of the first-fourth embodiments, the at leastone hydrocarbon resin has a Tg of about 40 to about 55° C., or 40-55° C.(e.g., 40, 42, 44, 45, 46, 48, 50, 52, 54, or 55° C.). In certainembodiments of the first-fourth embodiments, the at least onehydrocarbon resin comprises an aromatic hydrocarbon resin having a Tg ofabout 35 to about 60° C., 35-60° C., about 35 to about 50° C., 35-50°C., about 35 to about 45° C., or 35-45° C. In certain preferredembodiments of the first-fourth embodiments, the at least onehydrocarbon resin comprises an aliphatic hydrocarbon resin having a Tgof about 40 to about 60° C., 40-60° C., about 45 to about 60° C., 45-60°C., about 45 to about 55° C., or 45-55° C. As discussed further infraaccording to the first-fourth embodiments in addition to controlling theamount of hydrocarbon resin (c) used in the tread rubber compositions,it is also preferable to control the total amount of hydrocarbon resin(c) and oil (d) to within the amounts discussed elsewhere herein.

According to the first-fourth embodiments, one or more than onehydrocarbon resin may be utilized in the tread rubber composition andthe particular type or types of hydrocarbon resin may vary. When morethan one hydrocarbon resin is utilized, the above-discussed amountsshould be understood to refer to the total amount of all hydrocarbonresins. In preferred embodiments of the first-fourth embodiments, thehydrocarbon resin of (c) comprises an aliphatic resin, an aromaticresin, or a combination thereof.

In certain embodiments of the first-fourth embodiments, the hydrocarbonresin of (c) comprises an aliphatic resin optionally in combination withone or more additional resins selected from cycloaliphatic, aromatic,and terpene resins; in those embodiments of the first-fourth embodimentswherein one or more additional resins are present, the total amount ofsuch additional resin(s) is preferably no more than 5 phr, less than 5phr, less than 4 phr, less than 3 phr, less than 2 phr, or less than 1phr (and in each instance no more than 10% by weight, preferably no morethan 5% by weight of the overall amount of hydrocarbon resin of (c)). Inother embodiments of the first-fourth embodiments, the hydrocarbon resinof (c) consists of (only) an aliphatic resin or aliphatic resins. Whenan aliphatic resin is used, one or more than one aliphatic resin may beutilized. In certain embodiments of the first-fourth embodiments, thehydrocarbon resin excludes any terpene resin (i.e., 0 phr of terpeneresin is present in the tread rubber composition). As used herein, theterm aliphatic resin should be understood to include both aliphatichomopolymer resins and aliphatic copolymer resins. An aliphaticcopolymer resins refers to a hydrocarbon resin which comprises acombination of one or more aliphatic monomers in combination with one ormore other (non-aliphatic) monomers, with the largest amount of any typeof monomer being aliphatic. An aliphatic copolymer resin would include ahydrocarbon resin having 45% by weight aliphatic monomers, in additionto 25% by weight cycloaliphatic monomers and 30% by weight aromaticmonomers as well as a hydrocarbon resin having 55% by weight aliphaticmonomers, in addition to 30% by weight cycloaliphatic monomers and 15%by weight aromatic monomers. In certain embodiments of the first-fourthembodiments, the hydrocarbon resin of (c) comprises one or morealiphatic copolymer resins having a majority by weight of all monomersbeing aliphatic (e.g., 51%, 55%, 60%, 65%, etc.). Non-limiting examplesof aliphatic resins suitable for use as the hydrocarbon resin in certainembodiments of the first-fourth embodiments include C5 fractionhomopolymer or copolymer resins, C5 fraction/C9 fraction copolymerresins, C5 fraction/vinyl aromatic copolymer resins (e.g., C5fraction/styrene copolymer resin), C5 fraction/cycloaliphatic copolymerresins, C5 fraction/C9 fraction/cycloaliphatic copolymer resins, andcombinations thereof. Non-limiting examples of cycloaliphatic monomersinclude, but are not limited to cyclopentadiene (“CPD”) anddicyclopentadiene (“DCPD”). Exemplary aliphatic resins are commerciallyavailable from various companies including Chemfax, Dow ChemicalCompany, Eastman Chemical Company, ldemitsu, Neville Chemical Company,Nippon, Polysat Inc., Resinall Corp., and Zeon under various tradenames.

In certain embodiments of the first-fourth embodiments, the hydrocarbonresin of (c) comprises a C5 fraction homopolymer resin, C5 fractioncopolymer resin (e.g., C5 in combination with one or more of theabove-mentioned monomers such as C9 fraction, DCPD, CPD, andcombinations thereof), or a combination thereof. In other embodiments ofthe first-fourth embodiments, the hydrocarbon resin of (c) consists of aC5 fraction homopolymer resin, C5 faction copolymer resin (e.g., C5 incombination with one or more of the above-mentioned monomers such as C9fraction, DCPD, CPD, and combinations thereof), or a combinationthereof.

In certain other preferred embodiments of the first-fourth embodiments,the hydrocarbon resin of (c) comprises an aromatic resin optionally incombination with one or more additional resins selected from aliphatic,cycloaliphatic, hydrogenated aromatic, and terpene resins; in thoseembodiments of the first-fourth embodiments wherein one or moreadditional resins are present, the total amount of such additionalresin(s) is preferably no more than 5 phr, less than 5 phr, less than 4phr, less than 3 phr, less than 2 phr, or less than 1 phr (and in eachinstance no more than 10% by weight, preferably no more than 5% byweight of the overall amount of hydrocarbon resin of (c)). In otherembodiments of the first-fourth embodiments, the hydrocarbon resin of(c) consists of (only) an aromatic resin or aromatic resins. When anaromatic resin is used, one or more than one aromatic resin may beutilized. In certain embodiments of the first-fourth embodiments, thehydrocarbon resin excludes any terpene resin (i.e., 0 phr of terpeneresin is present in the tread rubber composition). As used herein, theterm aromatic resin should be understood to include both aromatichomopolymer resins and aromatic copolymer resins. An aromatic copolymerresins refers to a hydrocarbon resin which comprises a combination ofone or more aromatic monomers in combination with one or more other(non-aromatic) monomers, with the largest amount of any type of monomerbeing aromatic. An aromatic copolymer resin would include a hydrocarbonresin having 45% by weight aromatic monomers, in addition to 25% byweight cycloaliphatic monomers and 30% by weight aliphatic monomers aswell as a hydrocarbon resin having 55% by weight aromatic monomers, inaddition to 30% by weight cycloaliphatic monomers and 15% by weightaliphatic monomers. In certain embodiments of the first-fourthembodiments, the hydrocarbon resin of (c) comprises one or more aromaticcopolymer resins having a majority by weight of all monomers beingaromatic (e.g., 51%, 55%, 60%, 65%, etc.). Non-limiting examples ofaromatic resins suitable for use as the hydrocarbon resin (c) in certainembodiments of the first-fourth embodiments include coumarone-indeneresins and alkyl-phenol resins as well as vinyl aromatic homopolymer orcopolymer resins such as those including one or more of the followingmonomers: alpha-methylstyrene, styrene, ortho-methylstyrene,meta-methylstyrene, para-methylstyrene, vinyltoluene,para(tert-butyl)styrene, methoxystyrene, chlorostyrene, hydroxystyrene,vinylmesitylene, divinylbenzene, vinylnaphthalene or any vinyl aromaticmonomer resulting from C9 fraction or C8-C10 fraction. Non-limitingexamples of vinylaromatic copolymer resins include vinylaromatic/terpenecopolymer resins (e.g., limonene/styrene copolymer resins),vinylaromatic/C5 fraction resins (e.g., C5 fraction/styrene copolymerresin), vinylaromatic/aliphatic copolymer resins (e.g., CPD/styrenecopolymer resin, and DCPD/styrene copolymer resin). Non-limitingexamples of alkyl-phenol resins include alkylphenol-acetylene resinssuch as p-tert-butylphenol-acetylene resins, alkylphenol-formaldehyderesins (such as those having a low degree of polymerization). Exemplarysuch aromatic resins are commercially available from various companiesincluding Chemfax, Dow Chemical Company, Eastman Chemical Company,Idemitsu, Neville Chemical Company, Nippon, Polysat Inc., ResinallCorp., and Zeon under various trade names.

In certain preferred embodiments of the first-fourth embodiments, thehydrocarbon resin (c) comprises an aromatic resin based upon one or moreof the above-mentioned vinyl aromatic monomers (e.g., styrene,alpha-methylstyrene); in certain such embodiments at least 80% byweight, at least 85% by weight, at least 90% by weight, at least 95% byweight, at least 98% by weight, at least 99% by weight, or even 100% byweight of the monomers in the aromatic resin are aromatic monomers. Incertain embodiments of the first-fourth embodiments, the hydrocarbonresin (c) consists of an aromatic resin based upon one or more of theabove-mentioned vinyl aromatic monomers (e.g., styrene,alpha-methylstyrene); in certain such embodiments at least 80% byweight, at least 85% by weight, at least 90% by weight, at least 95% byweight, at least 98% by weight, at least 99% by weight, or even 100% byweight of the monomers in the aromatic resin are aromatic monomers. Incertain embodiments of the first-fourth embodiments, the aromatic resinof (c) may include a hydrogenated form of one of the aromatic resinsdiscussed above (i.e., a hydrogenated aromatic resin). In otherembodiments of the first-fourth embodiments, the aromatic resin of (c)excludes any hydrogenated aromatic resin; in other words, in suchembodiments, the aromatic resin is not hydrogenated.

As mentioned above, in certain embodiments of the first-fourthembodiments, the at least one hydrocarbon resin of (c) comprises (i) anaromatic resin, an aliphatic resin, or a combination thereof, incombination with (ii) a cycloaliphatic resin. Non-limiting examples ofcycloaliphatic resins include DCPD and CPD homopolymer and copolymerresins. The amount of any cycloaliphatic resin used in (c) is preferablylimited. According to the first-fourth embodiments, the total amount ofany cycloaliphatic resin used in combination with the aromatic resin ispreferably no more than 5 phr, less than 5 phr, less than 4 phr, lessthan 3 phr, less than 2 phr, or less than 1 phr (and in each instance nomore than 20% by weight, preferably no more than 15% or no more than 10%by weight of the overall amount of hydrocarbon resin of (c)).

As mentioned above, in certain embodiments of the first-fourthembodiments, the at least one hydrocarbon resin of (c) comprises (i) anaromatic resin, an aliphatic resin, or a combination thereof, incombination with (ii) a terpene resin. Non-limiting examples of terpeneresins include alpha-pinene resins, beta-pinene resins, limonene resins(e.g., L-limonene, D-limonene, dipentene which is a racemic mixture ofL- and D-isomers), beta-phellandrene, delta-3-carene, delta-2-carene,and combinations thereof. The amount of any terpene resin used in (c) ispreferably limited. According to the first-fourth embodiments, the totalamount of any terpene resin used in combination with the aromatic resinis preferably no more than 5 phr, less than 5 phr, less than 4 phr, lessthan 3 phr, less than 2 phr, or less than 1 phr (and in each instance nomore than 20% by weight, preferably no more than 15% or no more than 10%by weight of the overall amount of hydrocarbon resin of (c)). Asmentioned above, in preferred embodiments of the first-fourthembodiments, the hydrocarbon resin (c) includes no terpene resin (i.e.,0 phr).

In certain preferred embodiments of the first-fourth embodiments, thehydrocarbon resin (c) has a softening point of about 70 to about 120°C., 70-120° C. (e.g., 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, or120° C.), preferably about 75 to about 115° C., or 75-115° C. (e.g., 75,80, 85, 90, 95, 100, 105, 110, or 115° C.). Generally the softeningpoint of a hydrocarbon resin will have a relationship to its Tg suchthat the Tg is lower than its softening point, and such that the lowerthe Tg the lower the softening point. As a non-limiting example, for twohydrocarbon resins having Tg's of 70 and 100° C., the resin with the Tgof 70° C. will have a lower softening point than the resin with the Tgof 100° C. In certain embodiments of the first-fourth embodiments, thehydrocarbon resin comprises an aliphatic hydrocarbon resin having asoftening point of about 90 to about 120° C., 90-120° C. (e.g., 90, 95,100, 105, 110, 115, or 120° C.), about 95 to about 115° C., 95-115° C.(e.g., 95, 100, 105, 110, or 115° C.), about 95 to about 110° C., or95-110° C. (e.g., 95, 100, 105 or 110° C.). In certain embodiments ofthe first-fourth embodiments, the hydrocarbon resin comprises anaromatic hydrocarbon resin having a softening point of about 70 to about100° C., 70-100° C. (e.g., 70, 75, 80, 85, 90, 95, or 100° C.), about 75to about 95° C., 75-95° C. (e.g., 75, 80, 85, 90, or 95° C.), about 75to about 90° C., or 75-90° C. (e.g., 75, 80, 85, or 90° C.).

In certain embodiments of the first-fourth embodiments, the hydrocarbonresin (c) meets at least one of the following: (a) a Mw of about 1000 toabout 4000 grams/mole, 1000-4000 grams/mole (e.g., 1000, 1100, 1200,1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400,2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600,3700, 3800, 3900, or 4000 grams/mole), about 1000 to about 3000grams/mole, 1000-3000 grams/mole (e.g., (e.g., 1000, 1100, 1200, 1300,1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500,2600, 2700, 2800, 2900, or 3000 grams/mole), about 1000 to about 2500grams/mole, 1000-2500 grams/mole (e.g., 1000, 1100, 1200, 1300, 1400,1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, or 2500grams/mole), about 1100 to about 2000 grams/mole, or 1100-2000grams/mole (e.g., 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900,or 2000 grams/mole); (b) a Mn of about 700 to about 1500 grams/mole,700-1500 grams/mole (e.g., 700, 800, 900, 1000, 1100, 1200, 1300, 1400,or 1500 grams/mole), about 800 to about 1400 grams/mole, 800-1400grams/mole (e.g., 800, 900, 1000, 1100, 1200, 1300, or 1400 grams/mole),about 800 to about 1300 grams/mole, 800-1300 grams/mole (e.g., 800, 900,1000, 1100, 1200, or 1300 grams/mole), about 900 to about 1200grams/mole, or 900-1200 grams/mole (e.g., 900, 950, 1000, 1050, 1100,1150, or 1200 grams/mole); or (c) a polydispersity (Mw/Mn) of about 1 toabout 2.5, 1-2.5 (e.g., 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9,2, 2.1, 2.2, 2.3, 2.4, or 2.5), about 1.1 to about 2.2, 1.1-2.2 (e.g.,1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, or 2.2), about 1.1to about 2, 1.1-2 (e.g., 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or2), about 1.2 to about 2, or 1.2 to 2 (e.g., 1.2, 1.3, 1.4, 1.5, 1.6,1.7, 1.8, 1.9, or 2). In certain embodiments of the first-fourthembodiments, the hydrocarbon resin (c) has a Mw according to one of theranges provided above, in combination with a Mn according to one of theranges provided above, further in combination with a Mw/Mn according toone of the ranges provided above.

In certain embodiments of the first-fourth embodiments, the hydrocarbonresin (c) comprises an aliphatic resin (as discussed above) having anaromatic hydrogen content (as measured by 1H NMR) of about 5 to about25%, 5-25% (e.g., 5, 10, 15, 20, or 25%), about 10 to about 20%, 10-20%(e.g., 10, 12, 14, 16, 18, or 20%), about 10 to about 15%, or about10-15% (e.g., 10, 11, 12, 13, 14, or 15%). In other embodiments of thefirst-fourth embodiments, the hydrocarbon resin (c) comprises anaromatic resin (as discussed above) having an aromatic hydrogen content(as measured by 1H NMR) of at least about 40% by weight, at least 40% byweight (e.g., 40, 45, 50, 51, 55, 60% by weight, or more), about 40% toabout 65% by weight, 40-65% by weight (e.g., 40, 42, 44, 45, 46, 48, 50,52, 54, 55, 56, 58, 60, 62, 64, or 65% by weight), at least about 45% byweight, at least 45% by weight (e.g., 45, 50, 51, 55, 60% by weight, ormore), about 45% to about 65% by weight, 45-65% by weight (e.g., 45, 47,49, 50, 51, 53, 55, 57, 59, 60, 61, 63, or 65% by weight), at least 51%by weight (e.g., 51, 55, 60, 65% by weight, or more), about 51% to about65% (e.g., 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, or65%), 51-65%, about 51% to about 60%, 51-60% (e.g., 51%, 52%, 53%, 54%,55%, 56%, 57%, 58%, 59%, or 60%), about 51% to about 55%, or 51-55%(e.g, 51, 52, 53, 54, or 55%). The amounts of aromatic hydrogen areweight percentages of hydrogen atoms bonded to aromatic carbons, basedupon the total weight of hydrogen atoms present in the respectivehydrocarbon resin. According to such NMR measurement, a sample of theresin is dissolved in chloroform and the total amount of all hydrogens(i.e., aromatic hydrogen, aliphatic hydrogen, and olefinic hydrogen) is100%.

Oils

As mentioned above, according to the first-fourth embodiments, the treadrubber composition comprises less than 10 phr (e.g., 9, 8, 7, 6, 5, 4,3, 2, 1 or 0 phr) of oil. In certain embodiments of the first-fourthembodiments, the tread rubber composition comprises no more than 5 phrof oil (e.g., 5, 4, 3, 2, 1 or 0 phr). The term oil is meant toencompass both free oil (which is usually added during the compoundingprocess) and extender oil (which is used to extend a rubber). Thus, bystating that the tread rubber composition comprises less than 10 phr ofoil it be understood that the total amount of any free oil and anyextender oil is less than 10 phr. In certain embodiments of thefirst-fourth embodiments, the tread rubber composition contains onlyfree oil in one of the foregoing amounts (e.g., less than 10 phr, lessthan 5 phr, etc.). In other embodiments of the first-fourth embodiments,the tread rubber composition contains only extender oil in one of theforegoing amounts (e.g., less than 10 phr, less than 5 phr, etc.). Inthose embodiments of the first-fourth embodiments wherein anoil-extended rubber is used the amount of oil used to prepare theoil-extended rubber may vary; in certain such embodiments, the amount ofextender oil present in the oil-extended rubber (polymer) is 10-50 partsoil per 100 parts of rubber (e.g., 10, 15, 20, 25, 30, 35, 40, 45 or 50parts oil per 100 parts of rubber), preferably 10-40 parts oil per 100parts of rubber or 20-40 parts oil per 100 parts of rubber. When anoil-extended rubber is used in the elastomer component of the treadrubber composition disclosed herein, the amounts specified for (i), (ii)and (iii) should be understood to refer to the amounts of rubber onlyrather than the amounts of oil-extended rubber. As a non-limitingexample, extender oil could be used in an amount of 40 parts oil per 100parts rubber in an SBR for (i) which SBR is used in an amount of 15parts in the overall tread rubber composition and, thus, the amount ofoil contributed by the oil-extended SBR to the tread rubber compositionwould be described as 6 phr. As used herein, oil refers to bothpetroleum based oils (e.g., aromatic, naphthenic, and low PCA oils) aswell as plant oils (such as can be harvested from vegetables, nuts, andseeds). Plant oils will generally comprise triglycerides and the termshould be understood to include synthetic triglycerides as well as thoseactually sourced from a plant.

According to the first-fourth embodiments when one or more oils arepresent in the tread rubber composition, various types of processing andextender oils may be utilized, including, but not limited to aromatic,naphthenic, and low PCA oils (petroleum-sourced or plant-sourced).Suitable low PCA oils include those having a polycyclic aromatic contentof less than 3 percent by weight as determined by the IP346 method.Procedures for the IP346 method may be found in Standard Methods forAnalysis & Testing of Petroleum and Related Products and BritishStandard 2000 Parts, 2003, 62nd edition, published by the Institute ofPetroleum, United Kingdom. Exemplary petroleum-sourced low PCA oilsinclude mild extraction solvates (MES), treated distillate aromaticextracts (TDAE), TRAE, and heavy naphthenics. Exemplary MES oils areavailable commercially as CATENEX SNR from SHELL, PROREX 15, and FLEXON683 from EXXON MOBIL, VIVATEC 200 from BP, PLAXOLENE MS from TOTAL FINAELF, TUDALEN 4160/4225 from DAHLEKE, MES-H from REPSOL, MES from Z8, andOLIO MES S201 from AGIP. Exemplary TDAE oils are available as TYREX 20from EXXONMOBIL, VIVATEC 500, VIVATEC 180, and ENERTHENE 1849 from BP,and EXTENSOIL 1996 from REPSOL. Exemplary heavy naphthenic oils areavailable as SHELLFLEX 794, ERGON BLACK OIL, ERGON H2000, CROSS C2000,CROSS C2400, and SAN JOAQUIN 2000L. Exemplary low PCA oils also includevarious plant-sourced oils such as can be harvested from vegetables,nuts, and seeds. Non-limiting examples include, but are not limited to,soy or soybean oil, sunflower oil (including high oleic sunflower oil),safflower oil, corn oil, linseed oil, cotton seed oil, rapeseed oil,cashew oil, sesame oil, camellia oil, jojoba oil, macadamia nut oil,coconut oil, and palm oil. The foregoing processing oils can be used asan extender oil, i.e., to prepare an oil-extended polymer or copolymeror as a processing or free oil.

In those embodiments of the first-fourth embodiments wherein one or moreoils are present in the tread rubber composition, the Tg of the oil oroils used may vary. In certain embodiments of the first-fourthembodiments, any oil utilized has a Tg of about −40 to about −100° C.,−40 to −100° C. (e.g., −40, −45, −50, −55, −60, −65, −70, −75, −80, −85,−90, −95, or −100° C.), about −40 to about −90° C., −40 to −90° C.(e.g., −40, −45, −50, −55, −60, −65, −70, −75, −80, −85, or −90° C.),about −45 to about −85° C., −45 to −85° C. (e.g., −45, −50, −55, −60,−65, −70, −75, −80, or −85° C.), about −50 to about −80° C., or −50 to−80° C. (e.g., −50, −55, −60, −65, −70, −75, or −80° C.).

Preferably according to the first-fourth embodiments, the tread rubbercomposition contains less than 5 phr (e.g., 4.5, 4, 3, 2, 1, or 0 phr)of MES or TDAE oil, preferably no MES or TDAE oil (i.e., 0 phr). Incertain embodiments of the first-fourth embodiments, the tread rubbercomposition contains no petroleum oil (i.e., 0 phr) and instead any oilutilized is a plant oil. In certain embodiments of the first-fourthembodiments, the tread rubber composition contains soybean oil in one ofthe above-mentioned amounts. In certain embodiments of the first-fourthembodiments, the tread rubber composition contains no sunflower oil(i.e., 0 phr).

In certain embodiments of the first-fourth embodiments, the tread rubbercomposition includes one or more ester plasticizers. Suitable esterplasticizers are known to those of skill in the art and include, but arenot limited to, phosphate esters, phthalate esters, adipate esters andoleate esters (i.e., derived from oleic acid). Taking into account thatan ester is a chemical compound derived from an acid wherein at leastone —OH is replaced with an —O— alkyl group, various alkyl groups may beused in suitable ester plasticizers for use in the tread rubbercompositions, including generally linear or branched alkyl of C1 to C20(e.g., C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15,C16, C17, C18, C19, C20), or C6 to C12. Certain of the foregoing estersare based upon acids which have more than one —OH group and, thus, canaccommodate one or more than one O-alkyl group (e.g., trialkylphosphates, dialkyl phthalates, dialkyl adipates). Non-limiting examplesof suitable ester plasticizers include trioctyl phosphate, dioctylphthalate, dioctyl adipate, nonyl oleate, octyl oleate, and combinationsthereof. The use of an ester plasticizer such as one or more of theforegoing may be beneficial to the snow or ice performance of a tiremade from a tread rubber composition containing such ester plasticizerat least in part due to the relatively low Tg of ester plasticizers. Incertain embodiments of the first-fourth embodiments, the tread rubbercomposition includes one or more ester plasticizers having a Tg of −40°C. to −70° C. (e.g., −40, −45, −50, −55, −60, −65, or −70° C.), or −50°C. to −65° C. (e.g., −50, −51, −52, −53, −54, −55, −56, −57, −58, −59,−60, −61, −62, −63, −64, or −65° C). . In those embodiments of thefirst-fourth embodiments wherein one or more ester plasticizers isutilized the amount utilized may vary. In certain embodiments of thefirst-fourth embodiments, one or more ester plasticizers are utilized ina total amount of 1-12 phr (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or12 phr), 1-10, phr (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 phr), 2-6 phr(e.g., 2, 3, 4, 5, or 6 phr) or 2-5 phr (e.g., 2, 3, 4, or 5 phr). Incertain embodiments of the first-fourth embodiments, one or more esterplasticizers is used in combination with oil where the oil is present inan amount of 1 to less than 10 phr, or 1-5 phr. In other embodiments ofthe first-fourth embodiments, one or more ester plasticizers is usedwithout any oil being present in the tread rubber composition (i.e., 0phr of oil).

As mentioned above, according to the first embodiment disclosed herein,the total amount of hydrocarbon resin (c) and oil (d) is less than 50phr (e.g., 49, 45, 44, 40, 39, 35, 34, 30, 29, 25, 24, 20, 19, 15 phr,or less) and according to the second and third embodiments disclosedherein, the total amount of hydrocarbon resin (c) and oil (d) is no morethan 40 phr (e.g., 40, 39, 35, 34, 30, 29, 25, 24, 20, 19, 15 phr, orless). In certain embodiments of the first embodiment, the total amountof hydrocarbon resin (c) and oil (d) is no more than 40 phr (e.g., 40,39, 35, 34, 30, 29, 25, 24, 20, 19, 15 phr, or less) or no more than 30phr (e.g., 30, 29, 25, 24, 20, 19, or 15 phr, or less). In certainembodiments of the second and third embodiments, the total amount ofhydrocarbon resin (c) and oil (d) is no more than 30 phr (e.g., 30, 29,25, 24, 20, 19, or 15 phr, or less). In certain embodiments of thefirst-third embodiments, the total amount of hydrocarbon resin (c) andoil (d) is 11-40 phr (e.g., 11, 12, 13, 14, 15, 19, 20, 24, 25, 29, 30,34, 35, 39, or 40 phr), 11-30 phr (e.g., 11, 12, 13, 14, 15, 19, 20, 24,25, 29, or 30 phr), 11-25 phr (e.g., 11, 12, 13, 14, 15, 19, 20, 24, or25 phr), 15-40 phr (e.g., 15, 19, 20, 24, 25, 29, 30, 34, 35, 39, or 40phr), 15-30 phr (e.g., 15, 19, 20, 24, 25, 29, or 30 phr), or 15-25 phr(e.g., 15, 19, 20, 24, or 25 phr).

Cure Package

As discussed above, according to the first-fourth embodiments disclosedherein, the tread rubber composition includes (comprises) a curepackage. Although the contents of the cure package may vary according tothe first-fourth embodiments, generally, the cure package includes atleast one of: a vulcanizing agent; a vulcanizing accelerator; avulcanizing activator (e.g., zinc oxide, stearic acid, and the like); avulcanizing inhibitor; and an anti-scorching agent. In certainembodiments of the first-fourth embodiments, the cure package includesat least one vulcanizing agent, at least one vulcanizing accelerator, atleast one vulcanizing activator and optionally a vulcanizing inhibitorand/or an anti-scorching agent. Vulcanizing accelerators and vulcanizingactivators act as catalysts for the vulcanization agent. Variousvulcanizing inhibitors and anti-scorching agents are known in the artand can be selected by one skilled in the art based on the vulcanizateproperties desired.

Examples of suitable types of vulcanizing agents for use in certainembodiments of the first-fourth embodiments, include but are not limitedto, sulfur or peroxide-based curing components. Thus, in certain suchembodiments, the curative component includes a sulfur-based curative ora peroxide-based curative. In preferred embodiments of the first-fourthembodiments, the vulcanizing agent comprises a sulfur-based curative; incertain such embodiments, the vulcanizing agent consists (only) of asulfur-based curative. Examples of specific suitable sulfur vulcanizingagents include “rubbermaker's” soluble sulfur; sulfur donating curingagents, such as an amine disulfide, polymeric polysulfide, or sulfurolefin adducts; and insoluble polymeric sulfur. Preferably, the sulfurvulcanizing agent is soluble sulfur or a mixture of soluble andinsoluble polymeric sulfur. For a general disclosure of suitablevulcanizing agents and other components used in curing, e.g.,vulcanizing inhibitor and anti-scorching agents, one can refer toKirk-Othmer, Encyclopedia of Chemical Technology, 3rd ed., WileyInterscience, N.Y. 1982, Vol. 20, pp. 365 to 468, particularlyVulcanization Agents and Auxiliary Materials, pp. 390 to 402, orVulcanization by A. Y. Coran, Encyclopedia of Polymer Science andEngineering, Second Edition (1989 John Wiley & Sons, Inc.), both ofwhich are incorporated herein by reference. Vulcanizing agents can beused alone or in combination. Generally, the vulcanizing agents may beused in certain embodiments of the first-fourth embodiments in an amountranging from 0.1 to 10 phr, including from 1 to 7.5 phr, including from1 to 5 phr, and preferably from 1 to 3.5 phr.

Vulcanizing accelerators are used to control the time and/or temperaturerequired for vulcanization and to improve properties of the vulcanizate.Examples of suitable vulcanizing accelerators for use in certainembodiments of the first-fourth embodiments disclosed herein include,but are not limited to, thiazole vulcanization accelerators, such as2-mercaptobenzothiazole, 2,2′-dithiobis(benzothiazole) (MBTS),N-cyclohexyl-2-benzothiazole-sulfenamide (CBS),N-tert-butyl-2-benzothiazole-sulfenamide (TBBS), and the like; guanidinevulcanization accelerators, such as diphenyl guanidine (DPG) and thelike; thiuram vulcanizing accelerators; carbamate vulcanizingaccelerators; and the like. Generally, the amount of the vulcanizationaccelerator used ranges from 0.1 to 10 phr, preferably 0.5 to 5 phr.Preferably, any vulcanization accelerator used in the tread rubbercompositions of the first-fourth embodiments excludes any thiurams suchas thiuram monosulfides and thiuram polysulfides (examples of whichinclude TMTM (tetramethyl thiuram monosulfide), TMTD (tetramethylthiuram disulfide), DPTT (dipentamethylene thiuram tetrasulfide), TETD(tetraethyl thiuram disulfide), TiBTD (tetraisobutyl thiuram disulfide),and TBzTD (tetrabenzyl thiuram disulfide)); in other words, the treadrubber compositions of the first-fourth embodiments preferably containno thiuram accelerators (i.e., 0 phr).

Vulcanizing activators are additives used to support vulcanization.Generally vulcanizing activators include both an inorganic and organiccomponent. Zinc oxide is the most widely used inorganic vulcanizationactivator. Various organic vulcanization activators are commonly usedincluding stearic acid, palmitic acid, lauric acid, and zinc salts ofeach of the foregoing. Generally, in certain embodiments of thefirst-fourth embodiments the amount of vulcanization activator usedranges from 0.1 to 6 phr (e.g., 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4,4.5, 5, 5.5, or 6 phr), preferably 0.5 to 4 phr (e.g., 0.5, 1, 1.5, 2,2.5, 3 3.5, or 4 phr). In certain embodiments of the first-fourthembodiments, one or more vulcanization activators are used whichincludes one or more thiourea compounds (used in the of the foregoingamounts), and optionally in combination with one or more of theforegoing vulcanization activators. Generally, a thiourea compound canbe understood as a compound having the structure (R¹)(R²)NS(═C)N(R³)(R⁴)wherein each of R¹, R², R³, and R⁴ are independently selected from H,alkyl, aryl, and N-containing substituents (e.g., guanyl). Optionally,two of the foregoing structures can be bonded together through N(removing one of the R groups) in a dithiobiurea compound. In certainembodiments, one of R¹ or R² and one of R³ or R⁴ can be bonded togetherwith one or more methylene groups (—CH₂—) therebetween. In certainembodiments of the first-fourth embodiments, the thiourea has one or twoof R¹, R², R³ and R⁴ selected from one of the foregoing groups with theremaining R groups being hydrogen. Exemplary alkyl include C1-C6 linear,branched or cyclic groups such as methyl, ethyl, propyl, iso-propyl,butyl, iso-butyl, pentyl, hexyl, and cyclohexyl. Exemplary aryl includeC6-C12 aromatic groups such as phenyl, tolyl, and naphthyl. Exemplarythiourea compounds include, but are not limited to,dihydrocarbylthioureas such as dialkylthioureas and diarylthioureas.Non-limiting examples of particular thiourea compounds include one ormore of thiourea, N,N′-diphenylthiourea, trimethylthiourea,N,N′-diethylthiourea (DEU), N,N′-dimethylthiourea, N,N′-dibutylthiourea,ethylenethiourea, N,N′-diisopropylthiourea, N,N′-dicyclohexylthiourea,1,3-di(o-tolyl)thiourea, 1,3-di(p-tolyl)thiourea,1,1-diphenyl-2-thiourea, 2,5-dithiobiurea, guanylthiourea,1-(1-naphthyl)-2-thiourea, 1-phenyl-2-thiourea, p-tolylthiourea, ando-tolylthiourea. In certain embodiments of the first-fourth embodiments,the activator includes at least one thiourea compound selected fromthiourea, N,N′-diethylthiourea, trimethylthiourea,N,N′-diphenylthiourea, and N-N′-dimethylthiourea.

Vulcanization inhibitors are used to control the vulcanization processand generally retard or inhibit vulcanization until the desired timeand/or temperature is reached. Common vulcanization inhibitors include,but are not limited to, PVI (cyclohexylthiophthalmide) from Santogard.Generally, in certain embodiments of the first-fourth embodiments theamount of vulcanization inhibitor is 0.1 to 3 phr, preferably 0.5 to 2phr.

Preparing The Rubber Compositions

The particular steps involved in preparing the tread rubber compositionsof the first-fourth embodiments disclosed herein are generally those ofconventionally practiced methods comprising mixing the ingredients in atleast one non-productive master-batch stage and a final productivemixing stage. Similarly, the discussion herein of exemplary particularsteps involved in preparing the tread rubber compositions of thefirst-fourth embodiment should be understood as being equally applicableto the process of the fifth embodiment. In certain embodiments of thefirst-fourth embodiments, the tread rubber composition is prepared bycombining the ingredients for the rubber composition (as disclosedabove) by methods known in the art, such as, for example, by kneadingthe ingredients together in a Banbury mixer or on a milled roll. Suchmethods generally include at least one non-productive master-batchmixing stage and a final productive mixing stage. The termnon-productive master-batch stage is known to those of skill in the artand generally understood to be a mixing stage (or stages) where novulcanizing agents or vulcanization accelerators are added. The termfinal productive mixing stage is also known to those of skill in the artand generally understood to be the mixing stage where the vulcanizingagents and vulcanization accelerators are added into the rubbercomposition. In certain embodiments of the first-fourth embodiments, thetread rubber composition is prepared by a process comprising more thanone non-productive master-batch mixing stage.

In certain embodiments of the first-fourth embodiments, the tread rubbercomposition is prepared by a process wherein the master-batch mixingstage includes at least one of tandem mixing or intermeshing mixing.Tandem mixing can be understood as including the use of a mixer with twomixing chambers with each chamber having a set of mixing rotors;generally, the two mixing chambers are stacked together with the uppermixing being the primary mixer and the lower mixer accepting a batchfrom the upper or primary mixer. In certain embodiments, the primarymixer utilizes intermeshing rotors and in other embodiments the primarymixer utilizes tangential rotors. Preferably, the lower mixer utilizesintermeshing rotors. Intermeshing mixing can be understood as includingthe use of a mixer with intermeshing rotors. Intermeshing rotors refersto a set of rotors where the major diameter of one rotor in a setinteracts with the minor diameter of the opposing rotor in the set suchthat the rotors intermesh with each other. Intermeshing rotors must bedriven at an even speed because of the interaction between the rotors.In contrast to intermeshing rotors, tangential rotors refers to a set ofrotors where each rotor turns independently of the other in a cavitythat may be referred to as a side. Generally, a mixer with tangentialrotors will include a ram whereas a ram is not necessary in a mixer withintermeshing rotors.

Generally, the rubbers (or polymers) and at least one reinforcing filler(as well as any silane coupling agent and oil) will be added in anon-productive or master-batch mixing stage or stages. Generally, atleast the vulcanizing agent component and the vulcanizing acceleratorcomponent of a cure package will be added in a final or productivemixing stage.

In certain embodiments of the first-fourth embodiments, the tread rubbercomposition is prepared using a process wherein at least onenon-productive master batch mixing stage conducted at a temperature ofabout 130° C. to about 200° C. In certain embodiments of thefirst-fourth embodiments, the tread rubber composition is prepared usinga final productive mixing stage conducted at a temperature below thevulcanization temperature in order to avoid unwanted pre-cure of therubber composition. Therefore, the temperature of the productive orfinal mixing stage generally should not exceed about 120° C. and istypically about 40° C. to about 120° C., or about 60° C. to about 110°C. and, especially, about 75° C. to about 100° C. In certain embodimentsof the first-fourth embodiments, the tread rubber composition isprepared according to a process that includes at least onenon-productive mixing stage and at least one productive mixing stage.The use of silica fillers may optionally necessitate a separate re-millstage for separate addition of a portion or all of such filler. Thisstage often is performed at temperatures similar to, although oftenslightly lower than, those employed in the masterbatch stage, i.e.,ramping from about 90° C. to a drop temperature of about 150° C.

Tire Tread Properties

The use of the tire tread rubber composition of the first-thirdembodiments in tires, may result in a tire having improved or desirabletread properties. These improved or desirable properties may include oneor more of rolling resistance, snow or ice traction, wet traction, ordry handling. While these properties may be measured by various methods,the values referred to herein for rolling resistance, snow or icetraction, wet traction, and dry handling refer to tan δ values measuredat the following temperatures and according to the following procedures.Tan δ values can be measured with a dynamic mechanical thermalspectrometer (Eplexor® 500N from Gabo Qualimeter Testanlagen GmbH ofAhiden, Germany) under the following conditions: measurement mode:tensile test mode; measuring frequency: 52 Hz; applying 0.2% strain from50 to −5° C. and 1% strain from −5 to 65° C.; measuring temperatures of−30° C., 0° C., 30° C., and 60° C.; sample shape: 4.75 mm wide×29 mmlong×2.0 mm thick. Measurement is made upon a cured sample of rubber(cured for 15 minutes at 170° C.). A rubber composition's tan δ at −30°C. is indicative of its snow or ice traction when incorporated into atire tread, tan δ at 0° C. is indicative of its wet traction whenincorporated into a tire tread, tan δ at 30° C. is indicative of its dryhandling when incorporated into a tire tread and its tan δ at 60° C. isindicative of its rolling resistance when incorporated into a tiretread.

In certain embodiments of the first-third embodiments, the rubbercomposition has a value for tan δ at 60° C. of 0.09 to 0.23 (e.g., 0.09,0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21,0.22, or 0.23), 0.1 to 0.22 (e.g., 0.1, 0.11, 0.12, 0.13, 0.14, 0.15,0.16, 0.17, 0.18, 0.19, 0.2, 0.21, or 0.22), 0.1 to 0.21 (e.g., 0.1,0.11 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or 0.21), or0.1 to 0.15 (e.g., 0.1, 0.11, 0.12, 0.13, 0.14, or 0.15). In certainembodiments of the first-third embodiments, the value for tan δ at 60°C. is combined with at least one of the following: (a) a value for tan δat −30° C. of at least 2.5 times the tan δ at 60° C. value (e.g., 2.5times, 2.6 times, 2.7 times, 2.8 times, 2.9 times, 3 times, 3.1 times,3.2 times, 3.3 times, 3.4 times, 3.5 times, 3.6 times, 3.7 times, 3.8times, 3.9 times, 4 times, 4.1 times, 4.2 times, 4.3 times, 4.4 times,4.5 times, 4.6 times, 4.7 times, 4.8 times, 4.9 times, 5 times, 5.1times, 5.2 times, 5.3 times, 5.4 times, 5.5 times, 5.6 times, 5.7 times,5.8 times, 5.9 times, 6 times, or more); (b) a value for tan δ at 0° C.of at least 2.5 times the tan δ at 60° C. value (e.g., 2.5 times, 2.6times, 2.7 times, 2.8 times, 2.9 times, 3 times, 3.1 times, 3.2 times,3.3 times, 3.4 times, 3.5 times, 3.6 times, 3.7 times, 3.8 times, 3.9times, 4 times, 4.1 times, 4.2 times, 4.3 times, 4.4 times, 4.5 times,4.6 times, 4.7 times, 4.8 times, 4.9 times, 5 times, 5.1 times, 5.2times, 5.3 times, 5.4 times, 5.5 times, 5.6 times, 5.7 times, 5.8 times,5.9 times, 6 times, or more); or (c) a value for tan δ at 30° C. of atleast 1.1 times the tan δ at 60° C. value (e.g., 1.1 times, 1.2 times,1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9times, 2 times, or more); in certain such embodiments, the value for tanδ at 60° C. is combined with each of (a), (b), and (c). In certainembodiments of the first-third embodiments, one of the foregoing valuesfor tan δ at 60° C. (e.g., 0.09 to 0.23, 0.1 to 0.22, 0.1 to 0.21 or 0.1to 0.15) is combined with (a) a value for δ at −30° C. of between 2.5times and 6 times (e.g., 2.5 times, 2.6 times, 2.7 times, 2.8 times, 2.9times, 3 times, 3.1 times, 3.2 times, 3.3 times, 3.4 times, 3.5 times,3.6 times, 3.7 times, 3.8 times, 3.9 times, 4 times, 4.1 times, 4.2times, 4.3 times, 4.4 times, 4.5 times, 4.6 times, 4.7 times, 4.8 times,4.9 times, 5 times, 5.1 times, 5.2 times, 5.3 times, 5.4 times, 5.5times, 5.6 times, 5.7 times, 5.8 times, 5.9 times, or 6 times) the tan δat 60° C. value, or between 3 times and 5 times (e.g., 3 times, 3.1times, 3.2 times, 3.3 times, 3.4 times, 3.5 times, 3.6 times, 3.7 times,3.8 times, 3.9 times, 4 times, 4.1 times, 4.2 times, 4.3 times, 4.4times, 4.5 times, 4.6 times, 4.7 times, 4.8 times, 4.9 times, 5 times)the tan δ at 60° C. value. In certain embodiments of the first-thirdembodiments, one of the foregoing values for tan δ at 60° C. (e.g., 0.09to 0.23, 0.1 to 0.22, 0.1 to 0.21, or 0.1 to 0.15) is combined with (b)a value for δ at 0° C. of between 2.5 and 6 times (e.g., 2.5 times, 2.6times, 2.7 times, 2.8 times, 2.9 times, 3 times, 3.1 times, 3.2 times,3.3 times, 3.4 times, 3.5 times, 3.6 times, 3.7 times, 3.8 times, 3.9times, 4 times, 4.1 times, 4.2 times, 4.3 times, 4.4 times, 4.5 times,4.6 times, 4.7 times, 4.8 times, 4.9 times, 5 times, 5.1 times, 5.2times, 5.3 times, 5.4 times, 5.5 times, 5.6 times, 5.7 times, 5.8 times,5.9 times, 6 times) the tan δ at 60° C. value, or between 3 times to 5times (e.g., 3 times, 3.1 times, 3.2 times, 3.3 times, 3.4 times, 3.5times, 3.6 times, 3.7 times, 3.8 times, 3.9 times, 4 times, 4.1 times,4.2 times, 4.3 times, 4.4 times, 4.5 times, 4.6 times, 4.7 times, 4.8times, 4.9 times, 5 times) the tan δ at 60° C. value. In certainembodiments of the first-third embodiments, one of the foregoing valuesfor tan δ at 60° C. (e.g., 0.09 to 0.23, 0.1 to 0.22, 0.1 to 0.21, or0.1 to 0.15) is combined with (c) a value for δ at 30° C. of between 1.1and 2 times (e.g., 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, or 2 times) the tan δat 60° C. value, or between 1.3 and 1.8 (e.g., 1.3 times, 1.4 times, 1.5times, 1.6 times, 1.7 times, or 1.8 times) the tan δ at 60° C. value. Incertain embodiments of the first-third embodiments, one of the foregoingvalues for tan δ at 60° C. (e.g., 0.09 to 0.23, 0.1 to 0.22, 0.1-0.21,or 0.1 to 0.15) is combined with one of the foregoing values for tan δat −30° C., one of the foregoing values for tan δ at 0° C., and one ofthe foregoing values for tan δ at 30° C.

This application discloses several numerical range limitations thatsupport any range within the disclosed numerical ranges, even though aprecise range limitation is not stated verbatim in the specification,because the embodiments of the compositions and methods disclosed hereincould be practiced throughout the disclosed numerical ranges. Withrespect to the use of substantially any plural or singular terms herein,those having skill in the art can translate from the plural to thesingular or from the singular to the plural as is appropriate to thecontext or application. The various singular or plural permutations maybe expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims are generallyintended as “open” terms. For example, the term “including” should beinterpreted as “including but not limited to,” the term “having” shouldbe interpreted as “having at least,” the term “includes” should beinterpreted as “includes but is not limited to.” It will be furtherunderstood by those within the art that if a specific number of anintroduced claim recitation is intended, such an intent will beexplicitly recited in the claim, and in the absence of such recitationno such intent is present. For example, as an aid to understanding, thefollowing appended claims may contain usage of the introductory phrases“at least one” and “one or more” to introduce claim recitations.However, the use of such phrases should not be construed to imply thatthe introduction of a claim recitation by the indefinite articles “a” or“an” limits any particular claim containing such introduced claimrecitation to inventions containing only one such recitation, even whenthe same claim includes the introductory phrases “one or more” or “atleast one” and indefinite articles such as “a” or “an” (e.g., “a” or“an” should typically be interpreted to mean “at least one” or “one ormore”); the same holds true for the use of definite articles used tointroduce claim recitations. In addition, even if a specific number ofan introduced claim recitation is explicitly recited, those skilled inthe art will recognize that such recitation should typically beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, typicallymeans at least two recitations, or two or more recitations).Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, and C”would include but not be limited to systems that have A alone, B alone,C alone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). It will be further understood by those withinthe art that virtually any disjunctive word or phrase presenting two ormore alternative terms, whether in the description, claims, or drawings,should be understood to contemplate the possibilities of including oneof the terms, either of the terms, or both terms. For example, thephrase “A or B” will be understood to include the possibilities of “A”or “B” or “A and B.”

All references, including but not limited to patents, patentapplications, and non-patent literature are hereby incorporated byreference herein in their entirety.

While various aspects and embodiments of the compositions and methodshave been disclosed herein, other aspects and embodiments will beapparent to those skilled in the art. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting, with the true scope and spirit beingindicated by the claims.

What is claimed is:
 1. A tire tread rubber composition comprising: a.100 parts of an elastomer component comprising: i. at least 45 parts ofone or more styrene-butadiene rubbers having a silica-reactivefunctional group, and ii. 10-55 parts of guayule natural rubber, b. atleast one reinforcing silica filler in an amount of 50-150 phr, c. 11-40phr of at least one hydrocarbon resin having a Tg of about 35 to about60° C., d. less than 10 phr of oil, and e. a cure package. wherein (c)and (d) are present in a total amount of less than 50 phr.
 2. The tiretread rubber composition of claim 1, containing no more than 20 phr ofcarbon black filler.
 3. The tire tread rubber composition of claim 1,wherein (c) and (d) are present in a total amount of no more than 40phr.
 4. The tire rubber composition of claim 1, wherein thestyrene-butadiene rubber(s) having a silica-reactive functional grouphave a Tg of about −65 to about −40° C.
 5. The tire tread rubbercomposition of claim 1, wherein (i) consists of two styrene-butadienerubbers having a silica-reactive functional group in a total amount of50-80 phr.
 6. The tire tread rubber composition of claim 1, wherein (c)and (d) are present in a total amount of no more than 30 phr.
 7. Thetire tread rubber composition of claim 1, wherein (b) is present in atotal amount of 50-89 phr.
 8. The tire tread rubber composition of claim1, containing no more than 10 phr of reinforcing carbon black filler. 9.A tire tread rubber composition comprising: a. 100 parts of an elastomercomponent comprising: i. at least 50 parts, of one or morestyrene-butadiene rubbers having a silica-reactive functional group andeach having a Tg of about −65 to about −40° C., and ii. 10-50 parts ofguayule natural rubber, b. at least one reinforcing silica filler in anamount of 50-89 phr, c. 11-40 phr of at least one hydrocarbon resinhaving a Tg of about 35 to about 60° C., d. less than 10 phr of oil, ande. a cure package, wherein (c) and (d) are present in a total amount ofno more than 40 phr and the composition contains no more than 20 phr ofcarbon black filler.
 10. The tire tread rubber composition of claim 9,wherein (i) consists of two styrene-butadiene rubbers having asilica-reactive functional group in a total amount of 50-80 phr.
 11. Thetire tread rubber composition of claim 10, wherein the styrene-butadienerubber(s) having a silica-reactive functional group of (i) have a Mw of250,000 to 600,000 grams/mole.
 12. A tire tread rubber compositioncomprising: a. 100 parts of an elastomer component comprising: i. atleast 50 parts of two styrene-butadiene rubbers having a silica-reactivefunctional group each rubber having a Tg of about −65 to about −40° C.and a Mw of 250,000 to 600,000 grams/mole, ii. 10-50 parts of guayulenatural rubber, and iii. 0-5 phr of polybutadiene rubber. b. at leastone reinforcing silica filler in an amount of 50-89 phr, c. 11-40 phr ofat least one hydrocarbon resin having a Tg of about 35 to about 60° C.,d. less than 10 phr of oil, and e. a cure package, wherein (c) and (d)are present in a total amount of no more than 40 phr and the compositioncontains no more than 20 phr of carbon black filler.
 13. The tire treadrubber composition of claim 1, wherein the hydrocarbon resin of (c)comprises an aliphatic resin, an aromatic resin, or a combinationthereof.
 14. The tire tread rubber composition of claim 1, wherein theelastomer component includes 1-5 phr of polybutadiene rubber.
 15. Thetire tread rubber composition of claim 14, wherein the hydrocarbon resinof (c) comprises an aliphatic resin, an aromatic resin, or a combinationthereof.
 16. The tire tread rubber composition of claim 1, wherein thereinforcing silica filler of (b) has a CTAB surface area of greater than200 m²/g and a BET surface area of at least 150 m²/g.
 17. The tire treadrubber composition of claim 1, wherein the rubber composition has avalue for tan δ at 60° C. of 0.09-0.23 and meets at least one of thefollowing a. has a value for tan δ at −30° C. of at least 2.5 times thetan δ at 60° C. value; b. has a value for tan δ at 0° C. of at least 2.5times the tan δ at 60° C. value; or c. has a value for tan δ at 30° C.of at least 1.1 times the tan δ at 60° C. value.
 18. The tire treadrubber composition of claim 12, wherein the rubber composition has avalue for tan δ at 60° C. of 0.09-0.23 and meets at least one of thefollowing a. has a value for tan δ at −30° C. of at least 2.5 times thetan δ at 60° C. value; b. has a value for tan δ at 0° C. of at least 2.5times the tan δ at 60° C. value; or c. has a value for tan δ at 30° C.of at least 1.1 times the tan δ at 60° C. value.
 19. The tire treadrubber composition of claim 17, wherein each of (a), (b), and (c) aremet.
 20. A tire including a tread comprising the tire tread rubbercomposition of claim 1.